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How to use Azure Cosmos Emulator as a local MongoDb database 🌍

Mon, 30 Nov 2020 00:00:00 GMT

I recently was trying to prepare a demo which involved me having a local MongoDb database. I reviewed a few options and was about to choose one when I remembered I have Azure Cosmos DB Emulator installed and Cosmos DB supports MongoDb APIs.

Install if you haven’t already

You will need below requirements to be able to install the emulator:

Windows Server 2012 R2, Windows Server 2016, 2019 or Windows 8 and 10. Docker on Windows, Linux and macOS is also supported.
64-bit OS.
Minimum 2GB RAM.
At least 10GB available hard disk space.

If you’ve ticked all of above already, then head over here and install the latest version. If you stumbled upon any issues use the troubleshooting guide to find out what’s happening.

💡 Make sure you check for updates regularly since each new version might contain new features and bug fixes.

Starting the emulator

Normally you would use the Windows start menu to find your programs and start the application, however, for the emulator to support MongoDB APIs, you will need to pass the EnableMongoDbEndpoint argument.

You have a few options here:

Create a shortcut and pass the required arguments
Use command line to start it

I am going to use Windows Terminal. Run the below command to fire up the emulator with MongoDB support:

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& 'C:\Program Files\Azure Cosmos DB Emulator\CosmosDB.Emulator.exe' /EnableMongoDbEndpoint

You will be prompted to approve the emulator making changes to your system and once approved, you will see the emulator starting and the interface will open in your default browser.

Getting the connection string

The very first thing you’d see is the quick start which should look something like this:

What you’ll need is the Mongo Connection String. Copy that you’ll be ready to kick start. I am going to use the Node sample from the quick start to continue the rest of this guide, but you can use this straight away in your current code.

Creating a Node.js Web API project

Open up a command prompt in a new folder and initiate a project:

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npm init -y

The next thing to do is to install the dependencies:

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# linux or macOS
touch app.js

# Windows
echo "" > app.js

# install dependencies
npm install express mongodb body-parser

The app

We would have a simple application, since this tutorial is not a Node.js or Express.js focused, I will just brush on some steps here. Feel free to go through and understand each of these at your own pace.

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const Express = require("express");
const BodyParser = require("body-parser");
const MongoClient = require("mongodb").MongoClient;
const ObjectId = require("mongodb").ObjectID;
var app = Express();
app.use(BodyParser.json());
app.use(BodyParser.urlencoded({ extended: true }));
app.listen(5000, () => {});

What we have here is a simple web server which responds to http://localhost:5000. All we’re doing is initializing the MongoClient and a web server. Next thing we need to do is to establish a connection with MongoDB interface of our emulator:

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const Express = require("express");
const BodyParser = require("body-parser");
const MongoClient = require("mongodb").MongoClient;
const ObjectId = require("mongodb").ObjectID;
const CONNECTION_URL = "YOUR CONNECTION STRING";
const DATABASE_NAME = "cosmos_emulator_mongo";


var app = Express();
app.use(BodyParser.json());
app.use(BodyParser.urlencoded({ extended: true }));
var database, collection;

app.listen(5000, () => {
    MongoClient.connect(CONNECTION_URL, { useNewUrlParser: true }, (error, client) => {
        if(error) {
            throw error;
        }
        database = client.db(DATABASE_NAME);
        collection = database.collection("celebrities");
        console.log("Connected to `" + DATABASE_NAME + "`!");
    });
});

The next thing we do to make it simpler to run the app is to add a start script to our package.json:

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"scripts": {
    "start": "node app.js"
}

If you run npm start now, you should see the message connected to Connected to 'cosmos_emulator_mongo' printed on your console which means you’ve successfully connected to the MongoDb APIs.

Seed the database

First let’s create a JSON file which contains some celebrities 😎:

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[{
  "age": 18,
  "birth_place": "Harij, Gujarat, India",
  "birth_sign": "Pisces",
  "birth_year": "1996",
  "birthday": "September 28",
  "name": "Daxeel Soni",
  "occupation": "Developer of this API. More: www.daxeelsoni.in",
  "photo_url": "http://daxeelsoni.in/images/me.jpg"
}, {
  "age": 28,
  "birth_place": "Houston",
  "birth_sign": "Libra",
  "birth_year": "1987",
  "birthday": "September 28",
  "name": "Hilary Duff",
  "occupation": "TV Actress",
  "photo_url": "http://www.famousbirthdays.com/thumbnails/duff-hilary-medium.jpg"
}, {
  "age": 38,
  "birth_place": "Columbia",
  "birth_sign": "Libra",
  "birth_year": "1977",
  "birthday": "September 28",
  "name": "Young Jeezy",
  "occupation": "Rapper",
  "photo_url": "http://www.famousbirthdays.com/thumbnails/jeezy-young-medium.jpg"
}, {
  "age": 48,
  "birth_place": "Roanoke",
  "birth_sign": "Libra",
  "birth_year": "1967",
  "birthday": "September 28",
  "name": "Challen Cates",
  "occupation": "TV Actress",
  "photo_url": "http://www.famousbirthdays.com/thumbnails/cates-challen-medium.jpg"
}]

Now that we have our JSON file, let’s seed the database. Replace the initial connect code with this:

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app.listen(5000, () => {
  MongoClient.connect(
    CONNECTION_URL,
    {
      useNewUrlParser: true,
      sslValidate: false,
    },
    (error, client) => {
      if (error) {
        throw error;
      }
      database = client.db(DATABASE_NAME);
      collection = database.collection("celebrities");
      collection.estimatedDocumentCount({}, (erorr, numOfRecords) => {
        if (numOfRecords <= 0) {
          fs.readFile("./info.json", "utf8", (err, data) => {
            if (err) {
              console.log(`Error reading file from disk: ${err}`);
            } else {
              // parse JSON string to JSON object
              const celebrities = JSON.parse(data);

              collection.insertMany(celebrities, (error, result) => {
                if (error) {
                  console.log(`Error in saving seed data: ${error}`);
                }

                console.log(`Seed data inserted into the database!`);
              });
            }
          });
        } else {
          console.log(`Connected to database`);
        }
      });
    }
  );
});

All we’re doing here is to get the number of records in the collection and if there is nothing, read the JSON file and write it to the collection.

Don’t forget to add const fs = require('fs') at the top with other require statements.

Now if you run npm start would should see the application start and then the seed data inserted message.

Creating the endpoint

And now all we need is to add our get endpoint to be able to fetch our celebrities. Don’t forget to add it before you create your listener:

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app.get("/api/celebrities", (request, response) => {
    collection.find({}).toArray((error, result) => {
        if(error) {
            return response.status(500).send(error);
        }
        response.send(result);
    });
});

Testing the application

You’re now ready to get your celebrities via the API. Simply open a browser and head over to http://localhost:5000/api/celebrities or just use the below command:

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curl -X GET http://localhost:5000/api/celebrities

Summary

In this guide we saw how to use Azure Cosmos DB Emulator with MongoDb API to have a local MongoDb available for our local development and proof of concepts. Hope this has helped you save some time and also the trouble of installing yet another software on your system (of course if you already are using the emulator 😊).

Enjoy hacking and let us know what awesome projects you’re doing using the emulator.

PS: You can find the finished code in my GitHub repository here.

Access your clipboard on your other devices 😍 📋

Fri, 13 Nov 2020 00:00:00 GMT

How many times have you been working on multiple systems and realised you are trying to paste something which you have copied on the other system? Well with the help of this article you can now share your clipboard between your Windows and Mac devices 😎.

Windows to Windows

If you have multiple windows devices, it’s very easy. Simply open your control panel and search for Clipboard Settings.

Once opened, set the Sync across devices option to on. If you want to prevent sensitive data to be synced and do it on a case by case basis, set the Never automatically sync text that I copy option to on instead.

While you’re at it, turn clipboard history on too to have a beautiful clipboard history available by pressing Win+V.

Use the copied text

Now if you copy something into your clipboard, based on assuming you wanted to sync everything, simply paste, or open your clipboard history on the target device to see it.

⚠️ If you selected never automatically sync option, you can press Win+V to open up your clipboard history and select what you want to be synced across your devices after copying the items.

Additional tip

If you choose to use clipboard history, make sure you pin items you use frequently to save yourself some more time too.

Mac to Mac

If you’re a Mac user and want to achieve the same, you can use the Universal Clipboard.

It’s really simple, like we saw on windows setup.

Windows/Mac/Linux to Mac/Windows/Linux

If you use two different operating systems and want to simply share your content across, nothing works better than PASTEBIN.

This is a web tool that allows you to share your content across different devices with ease.

Warning

When using third party software whether it’s application or web app, never share secrets or your personal information.

Summary

We saw how to take some simple steps to increase our productivity and access any content we would like across our devices. Hope you benefit from this like I did and see you next time.

I've joined Microsoft as an Azure Technical Trainer 🗺️ 😍

Mon, 02 Nov 2020 00:00:00 GMT

The cat is out of the bag now, I’ve joined Microsoft as an Azure Technical Trainer. Some of you might be wondering why, and if so, this post is for you. I’ve decided to write down why I’ve made this decision and a bit about my 15+ years journey from high school to where I am now.

PS: We don’t have a Microsoft campus in Melbourne, but it didn’t prevent me photoshopping myself in 😜. Also, Satya Nadella was another motivation for me to join since we have a decent resemblance 😎.

Background

I started to write small programs when my brother bought a PC back in 1998. It was running MS-DOS and the first program I wrote could print a pyramid with stars on the console and was written in QBasic. From then, I was always amazed by people who write programs which can help others write their own, and working at Microsoft became one of my dream jobs.

Later on, I progressed through high school, pre-uni and then uni when I started my journey as a software engineer. I’ve started with C++, Turbo Pascal, FoxPro, Delphi, ASP Classic, PHP, and many other languages and ended up with, and finally ASP.Net MVC.

Throughout those years I became really interested to web development and have been active in that area so far. Of course that wasn’t the only thing I picked up, I have written windows desktop apps with ASP.Net web forms and Java Spring, Java Card applets to work with HSM and physical security devices, ActiveX, and many more I can’t even remember, not because I didn’t like them, but because I was really into learning new things and there were too many out there.

I wasn’t born in a wealthy family, so I had work summers and other free times to earn enough to go through my studies for the rest of the year. And we don’t have big companies represented in Iran, so working for Microsoft was became a wish in my bucket list.

Post uni

When I graduated from University with a Master’s degree in Information Security, I was hired by one of the well known software companies who were involved in banking industry. From there, I had jobs as software engineer, team lead and line manager and eventually I became the software engineering lead for one of the private banks’s PSP (payment service provider) company. But throughout all those years, I was on the lookout for an opportunity to migrate to another country and continue my professional career there.

Migrating to Australia

We considered Canada, US, and a few countries in Europe, but ended up pinning Australia on the map because of a few different reasons which suited our lifestyle and goals. So we sold/gave away most of our household items, rented out the apartment and packed our suitcases, jumped on a plane and ended up in Melbourne, Australia in 2015. I don’t want to go through how we got the Skilled Visa because it’s simply too long and brings back many not so good memories.

First job here

I immediately started applying for jobs here and without surprise, I was getting many calls, but not an actual opportunity that I liked. After one week, I had to bring down my expectations and start from scratch. I applied for a mid-level developer at a company and got in. This was after 3 weeks from our arrival and believe it or not is a record time for migrants to get a job.

Moving into consulting and public speaking

I didn’t stay there for long, as I didn’t want to waste any time following my goals. So I got into a consulting firm and eventually joined Readify (one of the best consulting firms in Australia) back in 2016. Because of my love for knowledge sharing, I got into public speaking starting from local meetups ended up at international conferences around the world. I am super proud of what I’ve achieved throughout these years and owe a big part to Readify and later on Telstra Purple. However, I still had my bucket list getting dust and wasn’t enjoying what I was doing as my full time job.

Decision to shift to developer advocacy

I was doing conference talks, blogs, and was involved in development community which has been a real pleasure, but managing all of that while having a full time job was really tough. So I started to search for similar roles and came across developer advocacy. However, this not a role which is very well known in Australia apart from big companies like Microsoft, Amazon AWS, IBM etc and some smaller ones like Auth0 and Twilio. I had a few discussions with different people to get an idea of what’s required to be able to score one of those jobs, but didn’t get a chance to find and apply for one.

When an opportunity presents itself

So I continued what I was doing, but still were on the lookout for something interesting which could help me do what I love to do. A few weeks back one of my friends who also works at Microsoft told me about a position on the Azure Technical Training team and I thought that’s something I would be really good at. It would be a bit of shift from web development, but the pros (working at Microsoft, sharing knowledge, and being close to what I love to do) convinced me to apply. I went through the interview and got an offer which made my year. This year has been really tough for me and my family and this event really helped us recover from these last few months of stress and anxiety.

Summary

So here I am, employed by my dream company, and doing what I love to do. It couldn’t have ended up better than this, I’ve already talked to my manager and he knows and supports my passion to be involved in development community, so this doesn’t mean I won’t be active on conferences and blog posts anymore. This amazing opportunity will help me grow in many ways as working at Microsoft and working with so many talented and amazing people would.

I just hope this has inspired a few of you fellow developers out there to never give up hope and follow your dreams however distant and impossible they seem 🤘🏽 💪🏽.

Get started with Vue 3 and Tailwindcss

Thu, 22 Oct 2020 00:00:00 GMT

Last week I wanted to setup a Vue.js v3 app with Tailwindcss and although many articles exists for that, I couldn’t get it done. The fact is that you need to use postcss to get your setup working, but with new version of Vue, the postcss config file is not picked up. So after a few try and errors, I finally got it working and thought to jot down what I went through to make it easier for my future self, and hopefully a few of my fellow developers around the world.

Vue CLI

You can setup your Vue project with simply importing the script tag and start coding, but I normally like to use Vue CLI to get started because it takes care of the many things for me and gives a really good starting point.

So let’s start by installing Vue CLI if you don’t have it already:

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npm install -g @vue/cli
# OR
yarn global add @vue/cli

This will install the Vue CLI for you and once that’s done, you’d be ready to create your project. If you already have CLI installed, make sure you update it first to get support for Vue v3 preview.

Creating the project

In order to create your project, you need to call the CLI and give your project name:

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vue create vue-tailwindcss

This command will start the wizard and asks you what version of Vue you want to use and what additional options you want to have.

You can choose between default seetings, or making a completely custom setup. I will normally choose custom which gives me more freedom as to what I want to setup.

From here press Entre on Choose Vue version, and select 3.x (Preview).

I would normally choose TypeScript, Babel, Linter, Unit and E2E testing optiuons, but feel free to setup how you like.

When it’s done go navigate into the folder or open it up with your editor of choice. Mince is VS Code.

Installing the required dependencies

At this point we need to install Tailwindcss:

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npm install tailwindcss

Create your style file

At this stage you’re ready to create your style file. I will put it next to my main.js for convinience.

Don’t forget to import it inside your main.js file:

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import "./main.css";
// ...

And now is the time to import the Tailwincss base and components in our css file:

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/* src/main.css */
@import "tailwindcss/base";
@import "tailwindcss/components";
@import "tailwindcss/utilities";

Postcss configuration

Many articles tell you to create a postcss.config.js or .postcssrc.js and set your config there, but with the new version of Vue CLI this doesn’t get picked up. For this part we simply need to update our package.json file:

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"postcss": {
  "plugins": {
    "tailwindcss": {},
    "autoprefixer": {}
  }
}

Import Tailwindcss components

You’re ready to use the Tailwindcss components now. So open up your hello-world.vue file and paste this code from their free gallery in:

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<!--
  Tailwind UI components require Tailwind CSS v1.8 and the @tailwindcss/ui plugin.
  Read the documentation to get started: https://tailwindui.com/documentation
-->
<div class="relative bg-white overflow-hidden">
  <div class="max-w-screen-xl mx-auto">
    <div class="relative z-10 pb-8 bg-white sm:pb-16 md:pb-20 lg:max-w-2xl lg:w-full lg:pb-28 xl:pb-32">
      <svg class="hidden lg:block absolute right-0 inset-y-0 h-full w-48 text-white transform translate-x-1/2" fill="currentColor" viewBox="0 0 100 100" preserveAspectRatio="none">
        <polygon points="50,0 100,0 50,100 0,100" />
      </svg>

      <div class="relative pt-6 px-4 sm:px-6 lg:px-8">
        <nav class="relative flex items-center justify-between sm:h-10 lg:justify-start">
          <div class="flex items-center flex-grow flex-shrink-0 lg:flex-grow-0">
            <div class="flex items-center justify-between w-full md:w-auto">
              <a href="#" aria-label="Home">
                <img class="h-8 w-auto sm:h-10" src="https://tailwindui.com/img/logos/workflow-mark-on-white.svg" alt="Logo">
              </a>
              <div class="-mr-2 flex items-center md:hidden">
                <button type="button" class="inline-flex items-center justify-center p-2 rounded-md text-gray-400 hover:text-gray-500 hover:bg-gray-100 focus:outline-none focus:bg-gray-100 focus:text-gray-500 transition duration-150 ease-in-out" id="main-menu" aria-label="Main menu" aria-haspopup="true">
                  <svg class="h-6 w-6" stroke="currentColor" fill="none" viewBox="0 0 24 24">
                    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 6h16M4 12h16M4 18h16" />
                  </svg>
                </button>
              </div>
            </div>
          </div>
          <div class="hidden md:block md:ml-10 md:pr-4">
            <a href="#" class="font-medium text-gray-500 hover:text-gray-900 transition duration-150 ease-in-out">Product</a>
            <a href="#" class="ml-8 font-medium text-gray-500 hover:text-gray-900 transition duration-150 ease-in-out">Features</a>
            <a href="#" class="ml-8 font-medium text-gray-500 hover:text-gray-900 transition duration-150 ease-in-out">Marketplace</a>
            <a href="#" class="ml-8 font-medium text-gray-500 hover:text-gray-900 transition duration-150 ease-in-out">Company</a>
            <a href="#" class="ml-8 font-medium text-indigo-600 hover:text-indigo-900 transition duration-150 ease-in-out">Log in</a>
          </div>
        </nav>
      </div>

      <!--
        Mobile menu, show/hide based on menu open state.

        Entering: "duration-150 ease-out"
          From: "opacity-0 scale-95"
          To: "opacity-100 scale-100"
        Leaving: "duration-100 ease-in"
          From: "opacity-100 scale-100"
          To: "opacity-0 scale-95"
      -->
      <div class="absolute top-0 inset-x-0 p-2 transition transform origin-top-right md:hidden">
        <div class="rounded-lg shadow-md">
          <div class="rounded-lg bg-white shadow-xs overflow-hidden" role="menu" aria-orientation="vertical" aria-labelledby="main-menu">
            <div class="px-5 pt-4 flex items-center justify-between">
              <div>
                <img class="h-8 w-auto" src="https://tailwindui.com/img/logos/workflow-mark-on-white.svg" alt="">
              </div>
              <div class="-mr-2">
                <button type="button" class="inline-flex items-center justify-center p-2 rounded-md text-gray-400 hover:text-gray-500 hover:bg-gray-100 focus:outline-none focus:bg-gray-100 focus:text-gray-500 transition duration-150 ease-in-out" aria-label="Close menu">
                  <svg class="h-6 w-6" stroke="currentColor" fill="none" viewBox="0 0 24 24">
                    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M6 18L18 6M6 6l12 12" />
                  </svg>
                </button>
              </div>
            </div>
            <div class="px-2 pt-2 pb-3">
              <a href="#" class="block px-3 py-2 rounded-md text-base font-medium text-gray-700 hover:text-gray-900 hover:bg-gray-50 focus:outline-none focus:text-gray-900 focus:bg-gray-50 transition duration-150 ease-in-out" role="menuitem">Product</a>
              <a href="#" class="mt-1 block px-3 py-2 rounded-md text-base font-medium text-gray-700 hover:text-gray-900 hover:bg-gray-50 focus:outline-none focus:text-gray-900 focus:bg-gray-50 transition duration-150 ease-in-out" role="menuitem">Features</a>
              <a href="#" class="mt-1 block px-3 py-2 rounded-md text-base font-medium text-gray-700 hover:text-gray-900 hover:bg-gray-50 focus:outline-none focus:text-gray-900 focus:bg-gray-50 transition duration-150 ease-in-out" role="menuitem">Marketplace</a>
              <a href="#" class="mt-1 block px-3 py-2 rounded-md text-base font-medium text-gray-700 hover:text-gray-900 hover:bg-gray-50 focus:outline-none focus:text-gray-900 focus:bg-gray-50 transition duration-150 ease-in-out" role="menuitem">Company</a>
            </div>
            <div>
              <a href="#" class="block w-full px-5 py-3 text-center font-medium text-indigo-600 bg-gray-50 hover:bg-gray-100 hover:text-indigo-700 focus:outline-none focus:bg-gray-100 focus:text-indigo-700 transition duration-150 ease-in-out" role="menuitem">
                Log in
              </a>
            </div>
          </div>
        </div>
      </div>

      <main class="mt-10 mx-auto max-w-screen-xl px-4 sm:mt-12 sm:px-6 md:mt-16 lg:mt-20 lg:px-8 xl:mt-28">
        <div class="sm:text-center lg:text-left">
          <h2 class="text-4xl tracking-tight leading-10 font-extrabold text-gray-900 sm:text-5xl sm:leading-none md:text-6xl">
            Data to enrich your
            <br class="xl:hidden">
            <span class="text-indigo-600">online business</span>
          </h2>
          <p class="mt-3 text-base text-gray-500 sm:mt-5 sm:text-lg sm:max-w-xl sm:mx-auto md:mt-5 md:text-xl lg:mx-0">
            Anim aute id magna aliqua ad ad non deserunt sunt. Qui irure qui lorem cupidatat commodo. Elit sunt amet fugiat veniam occaecat fugiat aliqua.
          </p>
          <div class="mt-5 sm:mt-8 sm:flex sm:justify-center lg:justify-start">
            <div class="rounded-md shadow">
              <a href="#" class="w-full flex items-center justify-center px-8 py-3 border border-transparent text-base leading-6 font-medium rounded-md text-white bg-indigo-600 hover:bg-indigo-500 focus:outline-none focus:border-indigo-700 focus:shadow-outline-indigo transition duration-150 ease-in-out md:py-4 md:text-lg md:px-10">
                Get started
              </a>
            </div>
            <div class="mt-3 sm:mt-0 sm:ml-3">
              <a href="#" class="w-full flex items-center justify-center px-8 py-3 border border-transparent text-base leading-6 font-medium rounded-md text-indigo-700 bg-indigo-100 hover:text-indigo-600 hover:bg-indigo-50 focus:outline-none focus:shadow-outline-indigo focus:border-indigo-300 transition duration-150 ease-in-out md:py-4 md:text-lg md:px-10">
                Live demo
              </a>
            </div>
          </div>
        </div>
      </main>
    </div>
  </div>
  <div class="lg:absolute lg:inset-y-0 lg:right-0 lg:w-1/2">
    <img class="h-56 w-full object-cover sm:h-72 md:h-96 lg:w-full lg:h-full" src="https://images.unsplash.com/photo-1551434678-e076c223a692?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=2850&q=80" alt="">
  </div>
</div>

Run the application

You’re all set, run npm run serve and when the CLI is finished compiling the app, open a browser window and head to https://localhost:8080 to see the Tailwindcss component:

Customisation

If you want to customise any of the default styles, you need to modify the theme. To do so, run:

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npx tailwind init

This will create a tailwind.config.js file for you in the root of your directory. To demo an example customisation, let’s say we want to add some space between the photo and the right hand side of the page. Currently the photo is having an position:absolute and right:0 because it has the lg:right-0 class.

So we want to add a new class which has 10% margin on the right hand side of the image. For that to work, we will need below code in our tailwindcss.config.js:

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module.exports = {
  future: {
    // removeDeprecatedGapUtilities: true,
    // purgeLayersByDefault: true,
  },
  purge: [],
  theme: {
    inset: {
      '0': 0,
      auto: 'auto',
      '1/10': '10%',
    },
    extend: {},
  },
  variants: {},
  plugins: [],
}

Pay attention that I’ve added a 1/10 with the value of 10% which we can use. Now all we need to do is to add lg:right-1/10 to the image container which pushes the image to the left by 10%:

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<div class="lg:absolute lg:inset-y-0 lg:right-1/10 lg:w-1/2">
</div>

And now it should look like this:

Summary

We saw how to add Tailwindcss library to our Vue 3 application created by Vue CLI. Hopefully this will help some of you out there facing the same issue as me. See you next time 👏🏽.

You can find the code in my GitHub repository.

Do you know about PowerToy Utilities? 💪🏻

Fri, 09 Oct 2020 00:00:00 GMT

If you’re a windows user like me, you might have heard of PowerToys Utilities from Microsoft. They are a set of utilities which come handy in many situations, but not many people know and use them. So I thought let’s write how and when I use them to help other people be more efficient too.

PowerToys utilities

Microsoft PowerToys are a set of small applications which helps windows users streamline their day to day activities and windows experience for greater productivity. However, these are not new. There were a set of tools in Widows 95 (yes I’m that old) which inspired this project.

Installation

Simply head to the Downloading and Release notes section on their GitHub repository, download the version you’re after and install it using its installer.

The latest version as of writing this article is v0.23.0. Once you get it installed, it will update itself on a regular basis.

So let’s see what are these and how you can use them.

Color picker

Color Picker is a handy little tool which allows you to pick a color from anywhere on your screen. As a web developer there are many times when I want to get the hex or rgb value of a background color, border, or other areas.

I used to use browser DevTools, but they only help you within the browser and if you want something from a document, picture or other files on your file system, then this tool will come in handy.

If you haven’t customised the default shortcuts, press Win + Shift + C to open the picker. Once opened, you can use your mouse scroll to zoom in and left click to copy the value to your clipboard.

Fancy zones

Fancy Zones allows you to create complex window layouts and quickly position your windows into those. This comes really handy if you have a super wide monitor setup.

To open it, press Win + ` and select your desired layout from the opened window. Once selected you can arrange your windows into those areas by pressing Win + ⬅ or Win + ➡.

💡 If the arrow keys didn’t work for you, simply select the option to override windows shortcuts in the settings. You can access the settings from clicking the PowerToys icon in your toolbar.

File explorer add-ons

File Explorer add-ons will enable SVG icon rendering and markdown preview for your file explorer. To see your preview pane simply click the view menu and click the preview pane.

Image resizer

Image Resizer is a really cool shell extension which allows you to quickly resize images. Simply right click on your image or images and resize them instantly.

keyboard manager

Keyboard manager allows you to create your own keyboard layout to increase your productivity. You can map keys and mix them however you like, of course you would need a keyboard with detachable key caps for a better use.

Open PowerToys settings and click on keyboard manager menu. First thing first, make sure it’s enabled.

Remap keys

If you want to remap a key, click on the remap keys, then click + button to add a key and then select what key you want that mapped to.

You can also map a single key to a shortcut, for example map V to Ctrl + V.

💡 Just remember that when you map a key to a shortcut, the combination remains even as part of other key presses. So if you’ve mapped V as above, then pressing Ctrl + V now means you’ve pressed Ctrl + V + V.

Remap shortcuts

You can map shortcuts as well, to do so, click on the remap a shortcut button and follow the same procedure. You can click on type button to press multiple keys and at the end you can specify which application this shortcut remap applies to.

PowerRename

PowerRename is another shell extension for balk renaming of files which offers search and replace and supports regex.

Select and right click on multiple files or folders, then click PowerRename. From the opened dialog, select your desired options and once you’re happy, click rename.

PowerToys run

This one is my favourite. It brings back the memories of the days we used to install add-ons on windows XP and 7 to add these sort of functionalities. First, make sure it’s enabled in the settings, and then press Alt + Space. A pop up will open and you can search for your application.

💡 Since I use this shortcut to select my open window to be able to move it between my monitors, I’ve set my shortcut to Ctrl + Alt + Space.

Shortcut guide

Shortcut guide is a quick and easy way to savailable shortcuts for the current state of the desktop. You can open it by pressing and holding down your Win key for 1 second.

Summary

Hopefully these tools will help you as much as they helped me. Have a great weekend ahead and till next article 👋🏻.

Find an item in an array with the new 'findIndex' method 🔎

Mon, 05 Oct 2020 00:00:00 GMT

Searching for items in an array has been the point of discussion for many years and debate on what is the best and optimum way for searching for objects has had many solutions, some effective and some not.

However, with the all new findIndex method on Array.prototype you have the flexibility to search for objects using your own comparison callback method.

The what

The findIndex method returns the index of the first element in an array if the callback method passed to it returns true, otherwise it returns -1.

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const isPerfectSquare = (num) => {
  return num > 0 && Math.sqrt(num) % 1 === 0;
}

console.log([1, 3, 8, 9, 12].findIndex(isPerfectSquare)); // 1
console.log([1, 6, 7, 10, 14].findIndex(isPerfectSquare)); // -1

There are two facts you should know:

This method does not run once it found the first matching element.
It does not change the original array.

Syntax

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array.findIndex(function(currentValue, index, arr), thisValue);

Parameters

function: This is your callback function which checks for a condition to match the element you’re after.
currentValue: This holds the current element’s value.
index: This is an optional parameter which holds the current index.
arr: This is also an optional parameter which holds the array that the current element belongs to.
thisValue: Yet another optional parameter, if a value is passed, it will be used as this value inside the function, otherwise undefined will be passed.

Return value

It will return the index of the found item or -1 if the callback function is not satisfied.

How it works under the hood?

When the findIndex is called with one or two arguments, the following steps are executed:

Let O be ? ToObject(this value)
Let len be ? LengthOfArrayLike(O)
If IsCallback(predicate) is false, throw a TypeError exception
Let k be 0
Repeat, while k < len
Let Pk be ! ToString(k)
Let kValue be ? Get(O, Pk)
Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, k, O »))
If testResult is true, return k
Set k to k + 1
Return -1

Take a selfie 🤳 using Image Capture API and a few lines of code

Sun, 06 Sep 2020 00:00:00 GMT

It’s been a while since I last wrote about Intersection Observer V2, partly because I had a lot on my plate and I was feeling exhausted and partly because I was working on my first PluralSight course on web performance for PWAs.

But I am back, and this time we’re going to review how to take a selfie from your webcam using Image Capture API.

Image Capture API

There are some really useful APIs which allow us to work with media like audio, video, etc. I will write about those too, but this time I wanted to show you how you can extract a frame from your video feed such as your webcam with a few lines of code.

Image Capture API enables us to capture an image or frame from video devices. In addition to capturing data, it also allows you to retrieve information about device capability such as image size, red-eye detection and whether or not there is flash turned on.

Usage

We need to take some actions to be able to work with media devices. First thing first we need to get a reference of the device:

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navigator.mediaDevices.getUserMedia({ video: true })
  .then(mediaStream => {
    // Do something with the stream.
  })

Next we need to get the visual parts of the media stream by calling getVideoTracks method of the mediaStream object:

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const track = mediaStream.getVideoTracks()[0];

Of course we’re assuming that the first item in the array is the one you want to use, but don’t worry if not, you can loop through all the tracks, find the one you need and either get it with its right index, or by calling getTrackById method.

After we’ve got our track, it’s time to capture our image. If you wanted to configure some of the settings on your media device such as zoom level, you need to do it now before capturing our image:

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const capabilities = track.getCapabilities();
// Check whether zoom is supported or not.
if(!capabilities.zoom) {
  return;
}

const zoom = capabilities.zoom.max - capabilities.zoom.min;

track.applyConstraints({ advanced : [{ zoom: zoom }] });

When we’re done with settings, we can then create an instance of the ImageCapture object:

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let imageCapture = new ImageCapture(track);

Once that’s done, you can capture an image from your video feed by calling the takePhoto method:

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imageCapture.takePhoto()
  .then(blob => createImageBitmap(blob))
  .then(imageBitmap => {
    // do something with the photo
  })
  .catch(error => console.error(error));

Permissions

Similar to other APIs you would need permission to be able to access the webcam on devices. If you didn’t see any pop up, make sure you give the camera permission to the site on your browser to be able to get your code working properly. You can try that with below demo.

Demo

You can see a working example of this in my CodePen below:

See the Pen Image Capture API by Yaser Adel Mehraban (@yashints) on CodePen.

I hope you’ve learnt a new thing or two and till next time 👋🏽.

Introducing the Intersection Observer V2 ⛌

Mon, 22 Jun 2020 00:00:00 GMT

As I mentioned in one of my other posts, Intersection Observer will report when an element appears in the viewport, after applying all overflow and CSS clips. However, there is no way currently to find out whether an item is being put on top of this element, or some filter is applied to it which may alter or obscure the element’s display.

Context

Intersection Observer is now widely used by developers especially since Safari added support a while back and it’s now available in all major browsers. If you want to be notified when an element appears in the viewport such as an image, if you want to lazy load it you can use this API. In its most basic form the code looks like this:

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const logIfIsInViewPort = (entries) => {
  for (const entry of entries) {
    if (entry.isIntersecting) {
      console.log(entry);
    }
  }
};

const observer = new IntersectionObserver(logIfIsInViewPort);
observer.observe(document.querySelector('.element-selector'));

The problem

As great as it sounds, this API is not perfect. For example it can’t tell you whether or not an element is covered by another content (which is called occluded), or if a filter is applied to it to hide or obscure it’s content (such as opacity, filter, transform, etc.).

This can lead to dangerous situations where some people might do fraud or abuse the web. So Intersection Observer V2 was born to prevent these types of scenarios.

Intersection Observer V2

As I said, the primary motivation for this API is to prevent those situations where a fraud might be possible, or people could abuse the user’s privacy in a way especially if the said content is put in an iframe.

Intersection Observer V2 works by tracking the actual visibility of the element, just like the end user would see it. By passing an option to it’s constructor, the collection of IntersectionObserverEntry will contain a new boolean called isVisible.

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const handler = (changes) => {
  for(const change in changes) {
    // feature detection
    if(typeof change.isVisible !== 'undefined') {
      if(change.isIntersecting && change.isVisible) {
        console.log(`Visible since ${change.time}`);
      } else {
        // fallback to v1 if not supported
        change.isVisible = true;
      }
    }
  }
}

const observer = new IntersectionObserver(handler, {
  threshold: [1.0],  
  trackVisibility: true, // this will give you the isVisible property
  delay: 100
});

observer.observe(document.querySelector('.target-element-selector'));

Additional parameters

The object which is passed in the constructor has a few properties:

threshold: A list of thresholds which will trigger a callback.
trackVisibility: A boolean indicating whether or not to track the visibility of the element.
delay: A number defining the minimum delay in milliseconds between notification for a given object.

💡 Note that tracking visibility is an expensive operation and should only be used when necessary. The performance implications can cause more harm than good if abused.

How does it determine visibility?

Determining whether the element is visible or not is not as simple as you might think. Based on the spec:

If false is passed as the value of trackVisibility, the element is considered visible.
If the target element has an effective transformation matrix other than 2D then the element is considered invisible.
If the target element or any of its children, has an effective capacity other than 1.0, then it’s considered invisible.
If the target element or any of its children has a filter applied, then it’s considered invisible.
If the browser cannot guarantee the target is fully visible, then it’s considered invisible.

What’s the catch?

This is in a draft state and still work in progress. Apart from Chrome, none of the other major browsers currently support it.

Summary

Although this hasn’t been implemented in most browsers yet, it’s a great tool to prevent some of the common attacks such as clickjacking or likejacking, or cursorjacking.

Chrome - where did save sessions go? 🤔

Wed, 17 Jun 2020 00:00:00 GMT

I remember a while back (not sure how long), Chrome had the ability to save all tabs when you closed the browser regardless of whether it was by accident or not. But they removed that ability and now if you close the window you will lose the tabs.

What now?

Well there are still some ways you can save your current tabs and open them next time you open a new Chrome window.

1. Small hack but works (most times 😁)

Open your task manager and kill the Chrome’s task. It’s a dirty hack but it works. When you open Chrome next time it asks you do you want to restore the last session and when you click the button, it will open all of your previously open tabs.

So first kill the task:

Later when you open a new window:

2. Save them as bookmarks

Yes, you read right. You can save all open tabs as bookmarks and open them all later when you come back. Simply press Ctrl + Shift + d in windows or ⌘ + Shift + d in Mac to save all your open tabs in a new bookmark folder.

Later on when you come back and open a new window, you can right click on the folder you created previously and select open all tabs:

⚠️ This technique won’t help you if your browser crashes for some reason.

3. I am too tired to do all of that

If you don’t want to open your task manager, or don’t want to use bookmarks, don’t worry. There are some extensions which can help you with that.

Tab Session Manager

Tab Session Manager is a Chrome extension which allows you to do:

Save and restore windows and tabs
Manage sessions with name and tags
Auto save when window is closed
Auto save at regular intervals
Import and export sessions
Compatibility with Firefox extension
Cloud sync

It also has Microsoft Edge and Firefox versions which is great.

Session Buddy

Session Buddy is a popular extension with more than 24K installs. It will do all of the above for you automatically in one place. Whether your browser crashes or you choose to close it manually.

Summary

Hope this helps you from a possible disaster if you have millions of tabs open at a time. If you are a tab person, check out my other article on managing your tabs in Chrome here. Until next time, 👋🏽.

Chrome - Arrange your tabs with tab groups 😍

Mon, 15 Jun 2020 00:00:00 GMT

If you’re one of those people with so many tabs open than you can manage, read on.

The why

For those of you who have many tabs open all at the same time and are struggling to keep a tab on your tabs, the time has come to get a bit more organised using this new feature in Chrome called tab groups.

The whole purpose has been to help users keep their tabs organised and easier to find them in their sea of open tabs.

How can I do it?

Simply right click your tab and select Add tab to tab group option. Then there will be a dot right before your tab. Click on the dot, a pop up will open in which you can select a colour for your tab group, and name your group.

If you are clicking on an existing group, you will have the following options in addition:

Add a new tab to the group
Ungroup tabs in a group
Close group
Move the group to a new window
Send feedback if you have any

I’ve demonstrated this in below video:

But I don’t see the option

If you can’t see the option, don’t worry, just go to chrome://flags, then search for tab groups and enable the option. It’s still experimental, but you can use it now.

Summary

Hope this will help you to keep a tab on your tabs and till next time 👋🏽.

Did you know about scroll to text? 📜

Sun, 14 Jun 2020 00:00:00 GMT

You probably have used fragments in links to point a link to a part of your page such as a heading. This technique is used in table of content for example and it’s a common pattern.

Background

To extend the current support for scrolling to an anchor element in a page, the W3C have proposed a solution which basically adds the ability to link to a DOM element with id, or textual content on a page to make it easier for browsers to understand what the users are interested and scroll there when they visit the page. In addition to make it visually easier to follow, they have added the highlight to the text so that users will know where to look at on first sight.

Scroll to Text Fragment

So that’s how Scroll to Text Fragment was born. It has been shipped to Chrome and Microsoft Edge called Scroll to Text Fragment which allows you to link to a specific text on a page, using a fragment provided in the URL. When the page is loaded, the browser highlights the text and scrolls it into view.

This is the generic syntax:

#:~:text=[prefix-,]textStart[,textEnd][,-suffix]
          context  |-------match-----|  context

💡 Square brackets indicate an optional parameter.

Here is an example:

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<a href="https://yashints.dev/#:~:text=Meet&text=Yas">
  Click to go to a specific portion of a page
</a>

And you can test it live by clicking here.

If you want to target an exact text:

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<a href="https://yashints.dev/#:~:text=almond%20croissant%20addict">
  Click to go to a specific portion of a page
</a>

Try it here.

You can also add an end text in which case the text directive refers to a range of text on the page.

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<a href="https://yashints.dev/#:~:text=Although,web%20developer">
  Click to go to a specific portion of a page
</a>

Try it here.

Use cases

Search engines

When search engines will link to pages which contain relevant information to the query, they will scroll and highlight that so the user will find it easier.

Citation / Reference links

Links are sometimes used as citations on some pages where the author wishes to enforce a claim by pointing to a reference such as Wikipedia. These reference pages can contains large chunks of text and finding the information can be difficult. So having the ability to scroll to that section and highlight it is really encouraging to readers to follow the links.

Sometimes you want to share a piece of text to someone for example by email or on social media, it’s really helpful to be able to link directly to the specific section rather than the whole page.

Nowadays people share short snippets directly in tweets or create screenshots which can contain more text and post those. With this they won’t need to do that since links can be more meaningful.

Summary

And that’s how the web is moving towards a better place where users are the centre of attention for us developers and the more we know how to make their lives easier the more they trust us to take care of it for them.

Enjoy your evening and till next time 👋🏽.

Links and JavaScript 🔗

Wed, 03 Jun 2020 00:00:00 GMT

I see some occasions where web developers who are a bit less familiar with accessibility use links incorrectly in different forms. So I thought let’s write a quick guide on Links in JavaScript apps.

Background

It’s safe to assume that anyone who’s used the web have seen them. They take users from one page to another either within the same application or to an external website. There were really hot when they were introduced back in 1966 by a team led by Douglas Engelbart.

In the early 1980s Ben Shneiderman, a computer scientist at the University of Maryland, with his graduate student Dan Ostroff were preparing a videodisk exhibit for a museum. It was then where they used a caption that had all the information and users could click on it to see the photo associated with it.

At first, this discovery was called embedded menu but that term was quickly replaced by hyperlink. Tim Berners-Lee cited Shneiderman’s hyperlink work in his spring 1989 manifesto for what would become the World Wide Web.

Back then, this feature was super hot and it still is. People use it without even thinking about it and it’s become a natural part of the web.

Enough background, tell me what’s this all about

Let’s review what they do:

As mentioned before they allow users to navigate between pages within a site or to an external one.
And more importantly they help search engines and bots to find resources and going from one page to another by following the links. Think of this as a giant maze where they need to blindly follow the links to discover stuff.
And last, the crawlers use them to understand the architecture of a site and the type of content they have. It’s a critical part of their decision making when assigning a page to a specific topic.

But how do you make a link?

`a` tag with `href`

Turns out it’s not as straightforward as one might think. The simplest way to put a link on your site is to use a good old <a> tag with a URL which it points to in the href attribute.

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<a href="/elsewhere">A good link, YES ╰(*°▽°*)╯</a>

`a` tag with `href` and event handler

For those with special circumstances, they might sprinkle a little bit of JavaScript on top and use an event handler to navigate the user programmatically:

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<a href="/elsewhere" onclick="goTo('elsewhere')">Okay ¯\_(ツ)_/¯</a>

This is fine as the link stays functional and you can upgrade the functionality using JavaScript.

`a` tag without `href`

But some people decide to remove the href attribute. This is not a good idea because you now prevented crawlers to find out where this link goes to:

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<a onclick="goTo('elsewhere')">Please don't ╯︿╰</a>

`a` tag with `href` but no link

In other occasions, people use the href attribute without a URL or with a pseudo URL:

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<a href="javascript:goTo('elsewhere')">Seriously? (⊙_⊙)？</a>

This is even worse than the previous case as it just confuses the hell out of every crawler out there.

using `button`

You might think it’s a good idea to use a button to navigate the user, but let me tell you, that’s not a good idea either. The rule of thumb is that if the purpose is to do something on the current page, it could be a button. But if it’s takes users to another page or to an external site, it should be a link.

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<button onclick="goTo('elsewhere')">But why? <( _ _ )> </button>

any other HTML element

It’s worth noting that you shouldn’t simulate a link using any other HTML element and add a click handler with JavaScript:

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<div onclick="goTo('elsewhere')">NOOOOOOOOOOOOOOOO!!!!!!!!!!!! (#`O′)</div>

This not only wrong for crawlers, but also messes up the screen readers and causes a lot of trouble for people with any vision impairment. So please just use a link with a proper URL.

What is a proper URL? I hear you ask

You saw we ruled out the pseudo URLs like javascript:doSomething(), but let’s take a look at URLs more closely.

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http://example.com/old-school-url

example.com/page#section

A URL contains these elements:

A protocol (optional), which defines the protocol to be used for navigation such as http, or https.
It also has a host, example.com or yashints.dev. A host is a name that one or some computers respond to. Usually it points to an IP address.
It has a path to specific asset on that computer such as an HTML file, an image, CSS file or a font. But that’s not always the case, sometimes the path is handled via JavaScript and is used to replace part of the content in a page. This technique is called Single Page Application or SPA.
Some URLs might contain another part such the second example above. That part which comes after the # sign, is called a fragment identifier. By itself a fragment identifier is not a piece of content. It just points to a specific part in the content such as a header.

💡 Because fragments are not suppose to point to different content, crawlers ignore them altogether. This means for single page applications where they use fragment like routing, crawlers don’t follow them and that’s why people use techniques such as server side rendering or SSR to allow crawlers become aware of the page’s content.

Summary

To sum it all up:

Use proper link markup, a tag with href attribute.
Do not use other HTML elements to navigate users.
Do not omit the href attribute on an anchor tag.
And last but not least, do not use fragment identifiers to load different content in SPAs if you can.

Hope you’ve enjoyed reading this and thanks for drooping by. Until next article, Ta.

Microsoft Build 2020 highlights 🔣

Sat, 23 May 2020 00:00:00 GMT

Microsoft Build went on fully online and it came with some really exciting announcements. For us developers some of these can bring massive efficiencies. So let’s see what’s on offer.

WSL2

Windows Subsystem for Linux v2 (aka WSL2) is here with a ton of awesome features allowing developers to have a really great experience working in a side by side Windows/Linux environment.

No Hyper-V image is needed to run docker containers
GPU Support
100% system call compatibility
Increased I/O performance

Linux GUI apps in Windows

This was really an exciting announcements. Microsoft is adding a full Linux Kernel to its Windows Subsystem for Linux v2 (aka WSL2) with GUI support and GPU acceleration.

This will be enabled without us having to use X11 forwarding and it’s mainly designed for developers to run Linux integrated development environments alongside regular Windows apps.

Image from Microsoft’s official blog

Winget, Microsoft’s package manager

This is probably one of those controversial topics where people will say: oh another package manager. But Microsoft believes they have considered all options and this decision was made with lots of considerations.

You can install winget via it’s App Installer package. You can also join their insider program which contains the winget by default.

You can easily add your package to this package manager by following their instructions on their GitHub repository and create a PR containing your package’s information and link to download.

Just so you know how excited people are, there are already 228 open PR’s and 541 closed. Of course not all of those PR’s have been packages, but even so, it’s a lot of packages submitted already.

Microsoft’s new PowerToys Run launcher

Microsoft just released a new Spotlight-like launcher app for Windows 10. This launcher is part of a series of apps which come with the PowerToys tool set.

It’s still preview, but you can install it today. Jump into this page and download the msi file, then install it.

Or if you like to do it a bit more fancy, just run this in your terminal:

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WinGet install powertoys

Remember this requires winget to be installed to work.

Once installed, press Alt + Space and you’ll get this beautiful launcher:

💡 You need to run it manually for the first time for now. This will get fixed once they release their GA version.

Alongside PowerToys Run, Microsoft also released a Keyboard Manager PowerToy which allows you to define shortcuts for your favourite actions, or remap keys like replacing A with B. Check out the other cool tools in their GitHub page.

Project Reunion

Microsoft announced Project Reunion, an effort to bring win32 desktop apps and its Universal Windows Platform (UWP) apps close together. From their page:

Project Reunion makes it easier to build a great Windows app by providing a unified platform for new and existing Win32 and UWP apps. It will unify access to existing Win32 and UWP APIs and make them available decoupled from the OS, via tools like NuGet.

Fluid framework

Microsoft is adding a new type of document to it’s Office suite called Fluid Framework. This allows multiple people to collaborate on a single document with fast speed and offers multiple types of elements like tables, graphs and lists in one place rather than having to use multiple apps for different reasons.

Apart from aforementioned features, it comes with ability to @mention someone to notify them of something, plus activity feeds for each document if you want to be notified of the changes.

And to emphasise their focus in bringing more to open source, they are making this framework open too.

Project Bonsai

Project Bonsai is Microsoft’s effort in creating a platform which lets developers and engineers create autonomous systems. It is a machine teaching service to create and optimize intelligence for industrial control systems. Through machine teaching, subject matter experts without an AI background can break down their expertise into steps and tasks that are imparted to AI agents.

Static Web Apps

Static Web Apps offers static Web applications powered by storage for hosting and Azure Functions as backend APIs. They also have the full pipeline on GitHub using GitHub actions to let you deploy your apps really fast.

These are some of the key features:

Free web hosting for static content like HTML, CSS, JavaScript, and images.
Integrated API support provided by Azure Functions.
First-party GitHub integration where repository changes trigger builds and deployments.
Globally distributed static content, putting content closer to your users.
Free SSL certificates, which are automatically renewed.
Custom domains to provide branded customizations to your app.
Seamless security model with a reverse-proxy when calling APIs, which requires no CORS configuration.
Authentication provider integrations with Azure Active Directory, Facebook, Google, GitHub, and Twitter.
Customizable authorization role definition and assignments.
Back-end routing rules enabling full control over the content and routes you serve.
Generated staging versions powered by pull requests enabling preview versions of your site before publishing.

Image from Microsoft blog

Others

There were dozens of other stuff announced, but here are some of the developer related ones:

Blazer WASM is released
MAUI makes mobile app development easier
Visual Studio is becoming Visual Studio Codespaces
GitHub Codespaces brings amazing developer experience right from your browser
GitHub Discussions for brainstorming feature ideas, help new users
Code scanning and secret scanning on GitHub on private repositories
GitHub Private Instances – a fully managed environment for enterprises
GitHub Actions for Azure are now integrated within: Visual Studio Code, Azure CLI, and the Azure Portal. This makes it easier to deploy from GitHub to Azure!

Hope this has given you some pointers to go play with some of these amazing features and till next time 👋🏽.

Swapping variables in JavaScript 🔁

Fri, 15 May 2020 00:00:00 GMT

There may be many different reasons why you’d want to swap two variables be it just changing two item’s location in an array or when sorting collections. The traditional way is just define a new variable, assign one value to it, put one of the items in the old place, then put the temp variable back in the new place. But my question is, is that the only way?

Traditionally

The old way of swapping two variables is done like below:

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let x = "Yas";
let y = "Hints";

let temp = x;
x = y;
y = temp;

console.log(x); // Hints
console.log(y); // Yas

There is nothing wrong with this approach unless you’re doing it frequently.

Without the temp variable

There is another way you could swap two variables without any temp variable. But this only works with numbers:

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let x = 10;
let y = 20;

x = x + y;
y = x - y
x = x - y;

console.log(x); // 20
console.log(y); // 10

This works two, but now we’re doing three additional operations to save some space, so you need to be careful when you use this one. Another thing to consider with this approach is the chance of having overflows with additions or subtractions (sum should be less than Number.MAX_SAFE_INTEGER which is 9007199254740991).

Bitwise `XOR`

Similar to above approach, you could use XOR to swap the two variables, but this also works only on numbers:

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let x = 3;
let y = 5;

x = x ^ y;
y = x ^ y;
x = x ^ y;

console.log(x); // 5
console.log(y); // 3

If you’re not familiar with XOR, it works on bits. When you perform XOR two bits, it evaluates to 1 if they are different, and evaluates to 0 if they’re the same.

x	y	XOR
0	0	0
1	1	0
0	1	1
1	0	1

So let’s see why this works.

x = x ^ y
y = y ^ x when x = (x ^ y), so the y = (x ^ y) ^ y which equals to x ^ (y ^ y) = x ^ 0 = x. So now our y is the old x.
x = x ^ y when according to our first step x is not x ^ y, and so x = (x ^ y) ^ x = y ^ (x ^ x) = y ^ 0 = y.

Is this better than the previous one, probably faster, but still limited to numbers only.

ES6 destructuring

Destructuring is an ES6 feature which is used a lot in many of the modern frameworks. In its core, it allows you to store array elements in variables.

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let x;
let y;

[x, y] = [1, 2, 3];

console.log(x); // 1
console.log(y); // 2

Now considering how we can use this to swap the elements of an array:

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let x = "Yas";
let y = "Hints";

[x, y] = [y , x];

console.log(x); // Hints
console.log(y); // Yas

This method is much elegant, but still creates two arrays to perform the swapping. So the efficiency might not be that good if you’re swapping many elements.

Summary

Just because a feature is available, doesn’t mean you should use it in every situation. Think about what is the most important factor in the solution you’re implementing. If it’s space, choose one which doesn’t take much, although it’s a bit slower.

If the memory doesn’t matter but speed is important, choose accordingly. But definitely consider the situation before deciding on your approach.

All you need to know about string in JavaScript 🧵

Mon, 11 May 2020 00:00:00 GMT

String is one of the primitive types in JavaScript and we use it in every project we work on no matter what. But how familiar are you with the methods available in JavaScript to work with a string variable? Let’s have a quick look at those in this article.

Introduction

A primitive value such as “Yas” doesn’t have any methods or properties, mainly because it’s not an object. But with JavaScript, methods and properties are available because it treats primitive values as objects.

Let’s have a look at the simplest method you have most definitely used:

String length

The length property returns the length of a string:

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const alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
console.log(alphabet.length); // 26

Pay attention on how length property is available on a primitive type. Not all languages are following the same principle when dealing with such behaviour though. In PHP we have helper functions:

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<?php
echo strlen("ABCDEFGHIJKLMNOPQRSTUVWXYZ");
?>

Finding a text in string

There are a few methods to help you find a sub-string in a String. Let’s go through them and see what are their differences:

`indexOf`

The indexOf method returns the index of the first occurrence of a specified text in a string:

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const txt = "Can you find Yas in 'dryasdust'?";
console.log(txt.indexOf('yas')); // 23

There a few points you need to know here. First, JavaScript counts positions from zero, and second, indexOf is case sensitive.

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const txt = "Can you find Yas in 'dryasdust'?";
console.log(txt.indexOf('Yas')); // 13

This method returns -1 if it can’t find the text:

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const txt = "There is no 0 in 11";
console.log(txt.indexOf('zero')); // -1

You can pass a second argument to let the indexOf know where to start looking for the text:

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const txt = "We have SQL and no-SQL databases!";
console.log(txt.indexOf('SQl', 10)); // 19

`lastIndexOf`

As the name suggests, lastIndexOf is used to find the last occurrence of a text in a string.

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const txt = "Can you find Jam in 'JamStack'?";
console.log(txt.indexOf('Jam')); // 21

This method also returns -1 if it can’t find the text you’re looking for, and takes a second parameter to start the search. However, since this method starts the search backward, the second parameter acts as cutting the string from that position to the end:

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const txt = "Can you find Jam in 'JamStack'?";
console.log(txt.lastIndexOf('Jam', 6)); // -1

`search`

The search method also searches the string for a text and returns the first occurrence of the text:

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const txt = "Can you find Jam in 'JamStack'?";
console.log(txt.search('Jam')); // 13

You might think that search and indexOf are the same. However, there are differences in these two:

search doesn’t accept any other parameter
indexOf cannot take powerful search values such as regular expressions

That’s right, search will accept regex as argument as well, for example, to perform a case insensitive search you might want to use search instead of indexOf:

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const txt = "There is Jam in JamStack!";
console.log(str.search(/jam/i)); // 9

console.log(txt.indexOf('jam')); // -1

You can also search for non usual patterns, e.g. finding any character that is not a word or whitespace:

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const txt = "There is Jam in JamStack!";
console.log(txt.search(/[^\w\s]/g)); // 24

`endsWith`

The endsWith methods checks whether the string ends with the specified text. It returns true if it does, and false if it doesn’t:

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const txt = "There is Jam in JamStack!";
console.log(txt.endsWith("Stack!")); // true

💡 This method is case sensitive.

`startsWith`

Similar to endsWith, this method checks whether a string starts with the specified text. This method is also case sensitive:

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const txt = "JamStack's got Jam";
console.log(txt.startsWith("JamStack")); // true

`includes`

includes allows you to check whether or not a string contains a specified text and is case sensitive:

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const txt = "There is Jam in JamStack!";
console.log(txt.includes("in")); // true
console.log(txt.includes("Jam")); // true
console.log(txt.includes("jam")); // false

`localeCompare`

localeCompare will compare two strings in the current locale. It returns a negative number indicating if the reference string occurs before the compare string, positive if it occurs after, and 0 if they are equivalent:

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const a = 'réservé'; 
const b = 'RESERVE';
console.log(a.localeCompare(b)); // 1
console.log(a.localeCompare(b, 'en', { sensitivity: 'base' })); // 0

Extracting sub-strings

There are three methods which allow you to extract part of a string.

`slice`

slice extracts part of a string and returns the extracted part in a new string. It takes two arguments, start position, and end position (the end position will not be included).

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const txt = "There is Jam in JamStack!";
console.log(txt.slice(9, 12)); // Jam

If you pass a negative value, it will start from the end of the string:

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const txt = "There is Jam in JamStack!";
console.log(txt.slice(-16, -13)); // Jam

You can omit the second parameter, and it will extract from start to the end of the string:

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const txt = "There is Jam in JamStack!";
console.log(txt.slice(16)); // JamStack!

`substring`

The substring method is similar to slice but it won’t accept negative indexes:

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const txt = "There is Jam in JamStack!";
console.log(txt.substring(16)); // JamStack!
console.log(txt.substring(9, 12)); // Jam

`substr`

substr method is similar to slice with one difference that the second parameter is the length of the text to be extracted and not the position:

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const txt = "There is Jam in JamStack!";
console.log(txt.substr(9, 3)); // Jam

And if you omit the second parameter, it will extract to the end of the string. Furthermore, if the index you pass is negative, it will count from the end:

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const txt = "There is Jam in JamStack!";
console.log(txt.substr(-9)); // JamStack!

`split`

Although this method is not directly used for extracting a text value, it’s good for splitting the string value by a character and return an array of substrings:

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const txt = "There is Jam in JamStack!";
const words = txt.split(' ');
console.log(words[4]); // JamStack!

A few points regarding this method:

The simplest case is a single character, also referred to as delimiter. For example you can split a tab separated value (TSV) by using str.split("\t").
If the separator contains multiple characters, that entire string needs to be found.
If the separator cannot be found, the return value is an array with one element containing the whole string.
If the separator appears at the beginning or end of the array, it still counts. Meaning the return value is an array with a string value, and one empty string item either at the start or at the end of the array.
If you pass an empty string " as the separator, it splits the string into single UTF-16 characters.

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const txt = "There is Jam in JamStack!";
console.log(txt.split('Jam')); // ["There is ", " in ", "Stack!"]
console.log(txt.split('test')); // ["There is Jam in JamStack!"]
console.log(txt.split('There')); // ["", " is Jam in JamStack!"]
console.log(txt.split('')); // ["T", "h", "e", "r", "e", " ", "i", "s", " ", "J", "a", "m", " ", "i", "n", " ", "J", "a", "m", "S", "t", "a", "c", "k", "!"]

Replacing string content

The replace method, as the name suggests, replaces a part of the string with the provided text:

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const txt = "Who's awesome!";
console.log(txt.replace("Who's", "You're")); // You're awesome!

💡 This method doesn’t change the original string, it returns a new one.

By default, it’s case sensitive and just replaces the first match:

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const txt = "This 🐶 is a good 🐶!";
console.log(txt.replace("This", "That")); // This 🐶 is a good 🐶!
console.log(txt.replace("🐶", "🐕‍🦺")); // This 🐕‍🦺 is a good 🐶!

To do a case insensitive replace or to replace all matches, you could use regex:

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const txt = "This 🐶 is a good 🐶!";
console.log(txt.replace(/THIS/i, "That")); // That 🐶 is a good 🐶!
console.log(txt.replace(/🐶/g, "🐩")); // This 🐩 is a good 🐩!

Case conversion

To convert a string to uppercase or lowercase you can use toUpperCase and toLowerCase respectively:

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const txt = "What's up bro!";
console.log(txt.toLowerCase()); // what's up bro!
console.log(txt.toUpperCase()); // WHAT'S UP BRO!

We also have toLocaleLowerCase and toLocaleUpperCase methods to convert according to user’s current locale:

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const dotted = 'İstanbul';
console.log(`EN-US: ${dotted.toLocaleLowerCase('en-US')}`); // "i̇stanbul"
console.log(`TR: ${dotted.toLocaleLowerCase('tr')}`); // "İSTANBUL"

Concatenation

You can use concat to join two strings together (like + operator):

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let message = "Hello" + " " + "World!";
console.log(message); // Hello World!
message = "Hello".concat(" ", "World!");
console.log(message); // Hello World!

Trimming and padding

`trim`

To remove whitespace from both sides of a string value, you can use the trim function:

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let message = "     Hello World!     ";
console.log(message.trim()); // "Hello World!"

💡 Whitespace in this context is all the whitespace characters (space, tab, no-break space, etc.).

`padStart`

The padStart method adds a given string at the start of the original string (multiple times, if needed), until the resulting string reaches the given length.

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const str1 = '5';
console.log(str1.padStart(6, '0')); // 000005

`padEnd`

The opposite of padStart is the padEnd.

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const txt = 'OMG Jam';
console.log(txt.padEnd(25, '.')); // OMG Jam..................
console.log('OMG Jam'.padEnd(10)); // "OMG Jam   "

Getting the string value

There are two methods where you can get the value of a string in JavaScript. You might say, Yas are you crazy, we already have the value in the variable. But remember that I said JavaScript treats a string variable as an object under the hood, so these methods come from the Object.prototype.

`valueOf`

The valueOf returns the primitive value of an object. For string values, JavaScript does it for you under the hood whenever you invoke a method which needs the primitive value. But you can also call this method to get it:

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const txt = "Yas";
console.log(txt.valueOf()); // "Yas"

`toString`

Similar to the above method, toString is used to return the value of a string.

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const stringObj = new String('Yas');
console.log(stringObj); // String {"Yas"}

console.log(stringObj.toString()); // "Yas"

`repeat`

This method is my personal favourite. You can pass a number to the repeat method and it returns your string repeated by that number. It’s really good if you want to have some long text generated for testing purposes:

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const txt = "Lorem ipsum faked,";
console.log(txt.repeat(5)); // Lorem ipsum faked,Lorem ipsum faked,Lorem ipsum faked,Lorem ipsum faked,Lorem ipsum faked,

Character methods

`charAt`

The charAt returns a new string consisting of the single UTF-16 code unit which is located at the index specified:

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const txt = "There is Jam in JamStack!";
const index = 4;
console.log(`The character at index ${index} is ${txt.charAt(index)}`); // "The character at index 4 is r"

`charCodeAt`

The charCodeAt returns an integer between 0 and 65535 representing the UTF-16 code unit at the given index:

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const txt = "There is Jam in JamStack!";
const index = 4;
console.log(`The character code at index ${index} is ${txt.charCodeAt(index)}`); //The character code at index 4 is 101

`codePointAt`

The codePointAt method returns a non negative integer representing the Unicode point value of the specified index:

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const icons = '☃★♲';
console.log(icons.codePointAt(1)); // "9733" 
'\uD800\uDC00'.codePointAt(0)  // 65536

`normalize`

And last, but not least, the normalize method returns the Unicode normalisation form of a string:

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const myAlias = '\u0059\u0061\u0073\u0068\u0069\u006e\u0074\u0073';
console.log(`${myAlias}`); // Yashints

Summary

Hope you enjoyed reading this and learnt a few tricks which could help you at what you do day to day. And let’s finish this article with a joke:

What do you call it when Wilhelm II makes a string of bad puns? 👉🏽 A Kaiser roll

Let's sort with JavaScript 🔢

Sun, 03 May 2020 00:00:00 GMT

There are many different sorting algorithms out there such as quick sort, merge sort, insertion sort, bubble sort, etc., that could be useful in our day to day life, writing code which gets shipped to production. Knowing all of them is not necessary, but if you have a basic understanding of each one, you can decide on the most efficient one for your scenario.

Introduction

Choosing a suboptimal sort algorithm could lead to longer completion time, code complexity, or worse, a program that crashes half way through an operation.

We use sorting algorithms everyday, Array.sort is one of the sort algorithms which is used to sort an array in ascending order. But that is not a solution for every scenario.

When choosing a sorting algorithm, we need to consider the complexity, or the number of operations performed (usually mentioned as O(x), which is read Big O of x) and also number of swaps along the way. So let’s review and implement some of the most used ones together and learn about their complexity.

Bubble sort

The way bubble sort works is very simple. You compare the first item of the collection with the second. If the first one is bigger, then swap the two. If not, move to the second item, and repeat the same. We keep repeating this until we reach the end of the list.

So far we have bubbled up the biggest item of the list to the far right side in its position. Now we repeat this for the rest of the items again until the list is sorted.

Let’s see this in action:

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function bubbleSort(list) {
  let len = list.length;

  for(let i = len - 1; i >= 0; i--) {
    for(let j = 1; j <= i; j++) {
      if(list[j - 1] > list[j]) {
        let temp = list[j - 1];
        list[j - 1] = list[j];
        list[j] = temp;
      }    
    }  
  }

  return list;
}

bubbleSort([7, 5, 2, 3, 9, 6]); // [2, 3, 5, 6, 7, 9]

As you can see this algorithm is not optimal, in fact it is one of the heaviest in terms of number of operations in worst-case scenarios. But in terms of swaps, it’s one of the best since it sorts in place.

The complexity of bubble sort in worst-case is O(n²), read as big O of n square, where n is the number of items in the collection.

However, in a best case scenario (already sorted collections), it will be O(n) with O(1) swaps.

Case	Complexity
Worst-case performance	O(n²) comparisons
	O(n²) swaps
Best-case performance	O(n) comparisons
	O(1) swaps
Average-case performance	O(n²) comparisons
	O(n²) swaps

Selection sort

Selection sort is really simple like bubble sort. We go through the list, find the index of the lowest element, then swap the lowest element with the first one. Now that the first item is sorted, we repeat this for all remaining elements.

Let’s see this in action:

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function selectionSort(list) {
  let minIndex, temp,
      len = list.length;
  
  for(let i = 0; i < len; i++) {
    minIndex = i;
    for(let j = i+1; j < len; j++) {
      if(list[j] < list[minIndex]) {
        minIndex = j;
      }
    }

    temp = list[i];
    list[i] = list[minIndex];
    list[minIndex] = temp;
  }

  return list;
}

selectionSort([11, 25, 12, 22, 64]); //[11, 12, 22, 25, 64]

Let’s see how the list is sorted in each iteration in the above example:

Sorted list	Unsorted sublist	Lowest elements
[]	[11, 25, 12, 22, 64]	11
[11]	[25, 12, 22, 64]	12
[11, 12]	[25, 22, 64]	22
[11, 12, 22]	[25, 64]	25
[11, 12, 22, 25]	[64]	64
[11, 12, 22, 25, 64]	[]

In terms of complexity, this algorithm remains the same regardless of which scenario we’re facing. Which is O(n²) for comparisons, and O(n) swaps. But if you look at the code, it’s self explanatory and simple and sometimes we just want exactly that. In terms or swaps, it’s less than bubble sort.

Case	Complexity
Worst-case performance	O(n²) comparisons
	O(n) swaps
Best-case performance	O(n²) comparisons
	O(n) swaps
Average-case performance	O(n²) comparisons
	O(n) swaps

Insertion sort

This is like when I play cards and someone is handing me the them one by one. I usually put them in my hand in order as I receive them. Insertion sort builds the final list one item at a time. This means it’s less efficient for large lists relative to it’s competitors such as quick sort, or merge sort.

However, it provides several advantages:

Simple implementation (we’ll get there shortly).
Efficient for small data sets.
More efficient than bubble or selection sorts.
Adaptive, i.e. efficient for already sorted collections.
In place.
Online, can sort a list as it receives it.

Let’s see how it works in action:

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function insertionSort(list){
  let i, len = list.length, item, j;

  for(i = 1; i < len; i++){
    item = list[i];
    j = i;

    while(j > 0 && list[j-1] > item) {
      list[j] = list[j-1];
      j--;
   }

   list[j] = item;
  }

  return list;
}

In terms of complexity, it’s similar to bubble sort in worst and average cases with O(n²) for both comparisons and swaps. But in best case, it’s really efficient with O(n) comparisons and O(1) swaps.

Case	Complexity
Worst-case performance	O(n²) comparisons
	O(n²) swaps
Best-case performance	O(n) comparisons
	O(1) swaps
Average-case performance	O(n²) comparisons
	O(n²) swaps

Merge sort

Merge sort is in the divide and conquer algorithms and is implemented with a recursive pattern. We break down the list into small pieces until you have one item in each piece. Then we merge them back together but will compare them and put the items in order.

It’s really easy to understand, but let’s see it in action:

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function mergeSort(list) {
   let len = list.length;
   if(len < 2)
      return list;
   let mid = Math.floor(len/2),
       left = list.slice(0,mid),
       right =list.slice(mid);
   
   return merge(mergeSort(left),mergeSort(right));
}

function merge(left, right) {
  let result = [],
      lLen = left.length,
      rLen = right.length,
      l = 0,
      r = 0;
  while(l < lLen && r < rLen) {
     if(left[l] < right[r]) {
       result.push(left[l++]);
     }
     else{
       result.push(right[r++]);
    }
  }  
  
  return result.concat(left.slice(l)).concat(right.slice(r));
}

Merge sort is much better in terms of complexity from previous algorithms. It takes O(n log n) operations to sort an array. In terms of memory needed, it’s O(n) total with O(n) auxiliary if we use array and O(1) if we use a linked list.

Case	Complexity
Worst-case performance	O(n log n)
Best-case performance	O(n log n)
Average-case performance	O(n log n)
Worst-case space	O(n) total, O(n) auxiliary with list, O(1) with linked list

Quick sort

Quick sort is similar to merge sort, with the difference that the we don’t split the collection in half. We choose a pivot point and split from there. Once we have chosen the pivot point, we put all smaller items to the left and all the larger items to the right of that.

That means that the pivot point itself is sorted now. We continue this for left and right side recursively until we have the full list sorted.

Choosing the pivot could be random, middle point, first, or last item of the list. There are many ways to do this each with their own pros and cons.

Let’s see this in action to better understand the difference:

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function quickSort(list, left, right) {
   let len = list.length, 
   pivot,
   partitionIndex;


  if(left < right) {
    pivot = right;
    partitionIndex = partition(list, pivot, left, right);
    
   //sort left and right
   quickSort(list, left, partitionIndex - 1);
   quickSort(list, partitionIndex + 1, right);
  }
  return list;
}

function partition(list, pivot, left, right) {
   let pivotValue = list[pivot],
       partitionIndex = left;

   for(let i = left; i < right; i++) {
    if(list[i] < pivotValue) {
      swap(list, i, partitionIndex);
      partitionIndex++;
    }
  }
  swap(list, right, partitionIndex);
  return partitionIndex;
}

function swap(list, i, j) {
   let temp = list[i];
   list[i] = list[j];
   list[j] = temp;
}

quickSort([11,8,14,3,6,2,7],0,6); 
//[2, 3, 6, 7, 8, 11, 14]

As you can see, the more efficient the algorithm gets, the more complex the implementation will be. In terms of complexity, it’s worst than merge sort in worst-case, and equal in average and best.

Case	Complexity
Worst-case performance	O(n²)
Best-case performance	O(n log n) with simple partition, O(n) with three-way partition
Average-case performance	O(n log n)
Worst-case space	O(n) auxiliary

Heap sort

Heap sort is a comparison based sort, you can think of it as an improved version of selection sort. It divides it’s input into a sorted and an unsorted region, then iteratively shrinks the unsorted region by extracting the largest item and inserting it into the sorted region.

The unsorted region is kept in heap data structure to more quickly find the largest item in each step.

💡 Since there is no heap data structure in JavaScript, we can use an array to represent it.

That was a mouthful, so let’s see it in action:

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function heapSort(list) {
  let len = list.length;
  let i = Math.floor(len / 2 - 1);
  let j = len - 1;

  while(i >= 0) {
    heapify(list, len, i);

    i--;
  }

  while(k >= 0) {
    [list[0], list[k]] = [list[k], list[0]];

    heapify(list, k, 0);

    k--;
  }

  return list;
}

function heapify(list, len, i){   
  let largest = i;
  let left = i * 2 + 1;
  let right = left + 1;

  if(left < len && > list[left] > list[largest]) {
    largest = left;
  }

  if(right < len && list[right] > list[largest]) {
    largest = right;
  }

  if(largest != i) {
    [list[i], list[largest]] = [list[largest], list[i]];

    heapify(list, len, largest);
  }

  return list;
}

In the above code snippet, heapify function compares three elements, the parent, and two children. It then makes sure that they are in the correct order for a max heap since we’re building the heap from bottom up.

Case	Complexity
Worst-case performance	O(n log n)
Best-case performance	O(n log n) distinct keys, O(n) with equal keys
Average-case performance	O(n log n)
Worst-case space	O(n) total, O(1) auxiliary

Summary

You should have a good understanding of these sort algorithms by now. If not, I recommend going through them again and try to write a few examples with a pen and paper. Don’t worry if you have trouble understanding the more complex ones like heap sort. It’s completely OK as I had the same trouble initially. But with practice and trying to implement them I learnt them at the end.

There are many other sort algorithms out there, so feel free to explore them and compare the way they work with what you’ve learnt so far.

Thanks for reading and enjoy sorting your collections.

⚡ All the images in this post are pulled from the algorithm’s Wikipedia pages.

Have you ever thought about for loops? ➰

Fri, 24 Apr 2020 00:00:00 GMT

Using a loop is almost a must in our day to day life. But have you ever thought what kind of loop should you use? Do you know the difference between enumerables and iterables? This article sheds some light in this space, so read on if you’re interested.

Background

Looping has seen quite a few changes from when I started programming. I remember using while loops and thinking wow, this is cool (I was printing starts on console using MS-DOS).

For loop is another way to iterate through a data structure which contains many items. But non of these methods iterate over the actual structure. They use a sequence, usually named i which mirrors the identifier for you.

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const fruits = ['🍉', '🍎', '🍌'];

for (let i = 0; i < fruits.length; i++) {
  console.log(fruits[i]);
}

// 🍉, 🍎, 🍌

Here i is an index which allows you to access the elements of fruits array and is not part of the array itself. But with progress on JavaScript towards more modern ways of programming, things have changes now. We have for...in, and for...of loops which use a different mechanism for going through items in a collection.

Concepts

Before we delve into these newer ways of iteration, we need to be on the same page around some concepts. So let’s go through them now:

Iterables: This is a kind of loop where we are performing a repetition. Meaning the same set of actions are performed on each item.
Enumerables: This is a kind of loop where we making mention of, or counting items one at a time. This means the collection’s elements can be distinctly identified and referenced.

That didn’t click for me at first, but after going through some examples, it finally made sense. If you consider a full pencil case, that’s an enumerable. When you line up at Aldi to pay, that line is an iterable. A wad of cash is an enumerable, whereas a row of keys on your keyboard is an iterable.

💡 In order for an object to be iterable, it MUST implement an @@iterator property which returns an iterator. An iterator object is one which has a next method which returns the next item in the collection. That’s why an object is not an iterable.

By now you should have started to see the pattern here. The best analogy I came across is:

😍 Enumerables are like rectangles whereas iterables are squares. This means all iterables are enumerables, however, not all enumerables are iterables.

`for...in`

So let’s start from enumerables. You can go through enumerables using for...in. The use case is mainly to go through key-value pairs in an object:

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const superCar = {
  make: 'Lamborghini',
  model: 'Veneno',
  year: '2020'
};

for (let key in superCar) {
  console.log(`${key} --> ${superCar[key]}`);
}

// make --> Lamborghini
// model --> Veneno
// year --> 2020

You can also use for...in to go through index values of an iterable like an array or a string:

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let fact = 'Lamborghini is the best!';

for (let index in fact) {
  console.log(`Index of ${fact[index]}: ${index}`);
}

// Index of L: 0
// Index of a: 1
// Index of m: 2
// Index of b: 3
// ...

💡 Beware that you can’t iterate on Symbol properties with for...in and that’s because Symbols are primitive data types that are always unique. They are generally used as private properties to avoid name clashes when inheritance is used.

Using `for...of`

This kind of loop is applicable to “iterable objects” meaning the item after of MUST be an iterable:

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const fruits = ['🍉', '🍎', '🍌'];

for (let fruit of fruits) {
  console.log(`${fruit} is delicious.`);
}

// 🍉 is delicious.
// 🍎 is delicious.
// 🍌 is delicious.

And again we can use it on strings, but with a slight difference:

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let fact = 'Yas';

for (let char of fact) {
  console.log(char);
}

// Y
// a
// s

Summary

We saw the difference between these two modern ways of looping through collections, let’s make more informed decisions as to use what where and write cleaner, more readable code 👊🏽.

Stay on top of performance with Lighthouse CI 🚦

Mon, 13 Apr 2020 00:00:00 GMT

You’ve spent many hours trying to improve your web performance and have got it to a good speed. What happens next? How do you ensure it remains in good shape especially if you’re working in a team with diverse backgrounds and level of coding.

Web performance must be monitored

I truly believe web performance shouldn’t be an item in your backlog, rather part of acceptance criteria on each story. That said, having discipline is hard when it comes to web performance. Each member of the team should be aware of dos and don’ts so that they can right code which doesn’t add a few seconds to current page load time, or user’s interactivity with the page.

In order to do so, you need to constantly monitor the performance of your application and when is a better time to do it than your CI/CD pipeline or when creating a pull request to get the code merged in (it’s worth mentioning having a CI/CD pipeline is not necessary to have a high quality, well written and performing site).

In addition to all of that, your site performs differently from your localhost, so you need to ensure you’re testing close to your actual environment.

Lighthouse CI

Lighthouse CI is a set of commands that make continuously running, asserting, saving, and retrieving Lighthouse results as easy as possible.

This is a great tool which allows you to run audits on your code base using command line, and raise an alert when someone unintentionally downgrades the performance.

What to measure?

There are countless metrics on which we could focus on. Some are user centric like time to interact, some are resource centric such as the size of your JavaScript or CSS files. Lighthouse CI allows us to easily focus on the size of the files. You can create two types of budgets:

1- Number of given resource: This will help you to for example enforce having only 3 JavaScript and 1 CSS file. 2- Size of a given resource: This budget will enforce that a given resource is of certain size, e.g. only 500kb.

How does it know?

You’re probably wondering how does Lighthouse CI know what to measure and when to raise an alert. This **||is done via a JSON file which is usually named budget.json, but you can choose any name you prefer.

Performance budget

The content of this file is an array of objects representing the budgets for a path. The content will look like below if you only have one path to assert:

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[
  {
    "resourceSizes": [
      ...
    ],
    "resourceCounts": [
      ...
    ]
  }
]

Within the resourceSizes and resourceCounts arrays, you can add individual objects that specify the resourceType and its budget. The budget can be any positive integer and the resourceType can be any of the following:

Resource type	Description
script	JavaScript files
document	HTML documents
image	Images
stylesheet	CSS files
font	Webfonts
media	Other media
other	Any other resource which doesn’t match the above, e.g. data transfers over Websocket connections
third-party	All resources from a third-party domain
total	All resources combined

For example, the following file will set a 200Kb budget for all scripts, a 500Kb for all images, and a 500Kb for all other resources. Then it sets the total network requests to be 25.

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[
  {
    "resourceSizes": [
      {
        "resourceType": "script",
        "budget": 200
      },
      {
        "resourceType": "image",
        "budget": 500
      },
      {
        "resourceType": "total",
        "budget": 500
      }
    ],
    "resourceCounts": [
      {
        "resourceType": "total",
        "budget": 25
      }
    ]
  }
]

As of Lighthouse 5.3 you can add a path property to select which pages the budget should apply to. This is very handy because it allows you to have a centralised budget file for all your pages.

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[
  {
    "path":"/*",
    "resourceSizes": [
      ...
    ],
    "resourceCounts": [
      ...
    ]
  },
  {
    "path":"/blog",
    "resourceSizes": [
      ...
    ],
    "resourceCounts": [
      ...
    ]
  },
  {
    "path":"/contact",
    "resourceSizes": [
      ...
    ],
    "resourceCounts": [
      ...
    ]
  }
]

How should you choose your numbers?

Finding the performance budget is not an easy task since it will depend on your application’s structure and bundling style. However, you can use this useful tool called Performance Budget Calculator to have a starting point. You might have to run the tool multiple time to each to a point where you’d be happy with the result. You don’t want to be too aggressive and also too complacent either.

Using the CI locally

You can install the CI locally with:

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npm install -g @lhci/cli

It also has a dashboard which shows you the historical runs, compares reports and store their results.

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npm install @lhci/server

Before running the CI, you need to have a configuration file to tell the tool what to test and where to find the budget file (you could also pass those individually without a config file, but it’d be a pain):

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// lighthouserc.json
{
  "ci": {
    "collect": {
      "numberOfRuns": 2,
      "startServerCommand": "yarn serve",
      "url": "http://localhost:8080"
    },
    "preset": "lighthouse:recommended"
  }
}

Then you can run the tool on your local web server by first running:

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lhci autorun --config=./lighthouserc.json

and then:

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lhci assert --no-lighthouserc --budgetsFile=budget.json

And you will get a result similar to below based on your app’s performance:

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2 result(s) for http://localhost:8080/

  ×  resource-summary.script.size failure for maxNumericValue assertion
     Keep request counts low and transfer sizes small
     Documentation: https://developers.google.com/web/tools/lighthouse/audits/budgets

        expected: <=102400
           found: 2416174
      all values: 2416174, 2416174


  ×  resource-summary.total.size failure for maxNumericValue assertion
     Keep request counts low and transfer sizes small
     Documentation: https://developers.google.com/web/tools/lighthouse/audits/budgets

        expected: <=512000
           found: 2437694
      all values: 2437694, 2437694

Assertion failed. Exiting with status code 1.

Using the tool on your PRs

I am focusing on GitHub using actions here. But you can apply this technique to Azure DevOps, CircleCI, TeamCity, or any other tool you’re using. For this to work you will need to have a GitHub flow in your git repository defined.

This article’s focus is not to teach you how to create a workflow, but here is the bare minimum you will need to have. Create a .yaml/.yml file in the .github/workflows folder, you can name it whatever you want. I usually name them after what’s their purpose, e.g. lighthouse.yml or lhci-performance-bot.yml.

But before we get to the content of our yaml file, let’s see what we need to do on each PR:

Pull down the code
Build the app
Deploy to a temporary site (I am using Netlify Preview here, but you can use others like staging slots on Azure App Service, etc)
Run Lighthouse CI on the site
Fail if the conditions are not met

For this to work, we need an application. So I just spun up a new Vue application using Vue CLI, then added my workflow to it and pushed it to a new GitHub repo.

Here is how my workflow looks like:

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name: Lighthouse CI

on:
  pull_request:
    branches: [master]

jobs:
  lighthouse:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v2
      - name: Setup Node 12
        uses: actions/setup-node@v1
        with:
          node-version: 12.x
      - name: Yarn Install and Build
        run: |
          yarn
          yarn build
      
      - name: Waiting for 200 from the Netlify Preview
        uses: jakepartusch/wait-for-netlify-action@v1
        id: waitFor200
        with:
          site_name: "lighthouse-ci-pr"

      - name: Audit URLs using Lighthouse
        uses: treosh/lighthouse-ci-action@v2
        with:
          urls: |
            $DEPLOY_URL/
            $DEPLOY_URL/about
          runs: 3
          budgetPath: ./budget.json
        env:
          DEPLOY_URL: ${{ steps.waitFor200.outputs.url }}

What is happening is that I am just creating an action on each PR. In this action, we need to pull down the code, install node, run yarn and yarn build to build the application, wait for Netlify to deploy our PR into a preview site, then get the URL and inject it into the next step.

I’m just using wait-for-netlify-action, but it’s not that hard to implement this part. Then we will be using the lighthouse-ci-action to run our audit on the paths we have specified.

Notice I am not using a Lighthouse configuration file in this workflow because it’s not needed. You can pass the parameters directly to the action like I’ve done above. I am just auditing the home and about pages since I’ve only got these two pages.

You can pass as many URL’s to this as you like, but if there are many of the, it makes more sense to add the config file back.

💡 Remember to setup Netlify for your site and set it to create a deployment for every PR. Then get the site id and pass it to the wait-for-netlify-action action.

Pro tip: When you setup your Vue CLI generated application which is using Vue Router, the non default routes won’t work if the user types them in the browser URL bar and hits enter. That’s because that route is handled on the client side and server doesn’t know about it. To fix that you need to add a URL rewrite rule to return your index.html for all legitimate routes.

In case of Netlify, just create a file named _redirects inside your public and add the following line to it.

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/*    /index.html   200

Result

I created a branch and pushed it up. Then created a PR and voila, the action kicked in and failed, since I have a large image on the about page.

I then reduced the size of the image and pushed the changes up. This time it passed.

Summary

We learned together how to use Lighthouse CI, a tool which allows you to run audits on your sites from command line in our CI/CD pipeline to make sure no one is downgrading the performance when they work on the application.

This way, we’re always on top of our game rather than creating backlog items to find the issues and fix them later.

In addition to that, your users are going to be happy and remain happy with their experience which is worth all the effort.

Hope you’ve enjoyed reading this and happy performance enforcement 👋🏽.

How I recovered a day's worth of work with git 🏥

Sun, 05 Apr 2020 00:00:00 GMT

I was working on a project a week ago and had a local branch (with a few commits) I was going to push to upstream to create a PR (pull request). However, after pulling down master and rebasing, I realised all of my code except my first commit is gone after rebase 😱.

Background

I had a local branch which I was working on. Since I’d made a few changes before end of the day, I committed those and went about to do some parenting.

The day after that, I restarted my work and had many other changes in a few other commits by the time I was ready to push my code to upstream. But before we do it, it’s our practice to pull down master and rebase in case there is any conflict, or changes made by someone else has had any side effects on the bit we’ve done.

Rebase

So I pulled down the master branch and rebased it directly from origin using (don’t do this at home please, I’ll explain later):

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git pull origin master --rebase

Once done, I realised I had some conflicts since someone else had worked on one of the files I’d modified. So I started the merge conflict process and made sure all was good. However, I didn’t realised that when I tested the web application, the latest code wasn’t refreshed, and I was seeing my own code (don’t ask me why, it’s an old code base and you need to rebuild and hard refresh every time you make a change).

Having seen all is good I created a PR and went for lunch. One of colleagues then reviewed the PR and since all my changes had gone apart from the small parts from yesterday’s commit, he approved and completed the PR.

Someone raised a bug

I was working on something else when I realised someone has raised a bug on the feature I’d implemented and when I checked the code I was in total shock since most of my code wasn’t there anymore. So I checked my local branch and saw that’s the case, in fact several of my commits were missing from that branch altogether.

Later I realised that I’d forgotten to add everything before committing 🤦🏽‍♂️. Just to clarify this was during a really crazy time where we were working day and night for over a week to deliver this project for all of our hospitals across Australia and New Zealand to monitor their resources in intensive care like number of available beds, ventilator, etc. I will tell you all about it once I find some time.

Initial try

I started by running:

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git reflog

I saw anything but my commits which expected because that commit command never had happened due to the files that weren’t added.

Checking stash

Next thing I checked was my stashed files:

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git stash list

This showed me there were two sets of stashed files.

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stash@{0}: WIP on elmah: 82eb0a4 Merged PR 426: Fixed pass change page
stash@{1}: WIP on availability: 87b2264 Dashboard is now grouping based on hospital category, has got a filter and a search box to search for hospitals

Then I looked into each of these with git stash show stash@{0} and git stash show stash@{1} but I didn’t see any of those.

checking git database

At this point I realised that I needed some help and I contacted Scott one of our git gurus to help me fine out what happened. He suggested we start by checking the database for any lost commit using:

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git fsck --lost-found

From the documentation:

—lost-found: Write dangling objects into .git/lost-found/commit/ or .git/lost-found/other/, depending on type. If the object is a blob, the contents are written into the file, rather than its object name.

This showed me a bunch of stuff including some dangling commits.

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Checking object directories: 100% (256/256), done.
Checking objects: 100% (4282/4282), done.
dangling tree 484106954fff79e5a4d7b8fd53fca05311e56e79
dangling blob d10124a92b82ccdcb1521ef814f815b75223e0f3
dangling commit 4c8288a8c30d4171c4935982e18ebd842a2c2811
dangling tree ae02e6d9b291775c9bc1eb1489ba341f8b033f48
dangling commit 2ec37c71f59766d55c09830a5b6e2c5e1c741a95
dangling blob 40c3c7ccbd197c78ceddf71c2be01b0db2114ba9
dangling tag a70363ef35f023e57e00fc625bee362c2e9e4bc9
dangling commit 1184e4a583e3d0f9cf9f3cb994a3375b16d122cd

So we started to go through some of these to find out which one contained the files I was after.

We checked out a few of those commits and couldn’t find what we were after. Then he suggested we check those dangling blobs which technically are a tree object containing a snapshot of everything in your current branch.

Checking git dangling blobs

You cannot checkout those objects, instead you need to use below command where the last part is the hash code of the blob you’re looking into:

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 git ls-tree -r d134e9e

You can copy this from the output of the previous command and you don’t need the whole hash value, just a few from the beginning.

The output of this command looks like this:

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100644 blob ea25f3a9fe6094d700588f33c340d32281a7614b    src/ARV.Database/ARV.Database.sqlproj.orig
100644 blob 2e47fe1d11bd2624065866591af00f80f16e5e1e    src/ARV.Web.Reach/Partials/hird/incident.form.campuses.list.html
100644 blob 2a6b2547ace20f6bbda788dc4e97e4a749281185    src/ARV.Web.Reach/Scripts/app/core/filters.js
100644 blob a366e78d88695f3c1a2b5617ec03fd24387f2323    src/ARV.Web.Reach/Scripts/app/hird/incident.form.controller.js
100644 blob 461c0e11c1ad64a0bee7bb7f57ba9a99314b1510    src/Arv.Cases.External/App_Data/Arv.Cases.External.XML
100644 blob 276ace5a9dae6be5613beebedcfbf5a64f8e4c4b    src/Arv.Services/Dtos/ReferenceDataDto.cs.orig
100644 blob 5336a10e14295222f28ef087643ac6696dc3cb73    src/Arv.Services/Reach/IIncidents.cs
100644 blob 6e186554f4de5347a754d39ebca1dd8867b7eb0a    src/Arv.Services/Reach/Incidents.cs
100644 blob cf70ac7b4af8f9d8e89c2d84e45a23bdaf7c99de    src/Arv.Services/ReferenceData.cs.orig
100644 blob 502e1286886624c6e0d46b9f65886fbc38b86bca    src/Arv.Web.Core/Controllers/Reach/IncidentController.cs
100644 blob 5ef3891af8afa82dd7cdfc45058a6186e4656c34    src/Arv.Web.Core/Controllers/ReferenceController.cs
100644 blob 49e5d63ba2e59c6389c21c24b81809326711fd27    src/Arv.Web.Core/Controllers/ReferenceController.cs.orig

After checking a few of these blobs, I finally found the one which contained a version of the file close to the finishing state (yes I had to redo some of my work, but now I had to spend half an hour instead of a day).

Checking the file

Once we found the blob, we had to check what’s the content of those files. You can do that using:

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git cat-file -p cf70ac7b

Now you can see the content printed out to the console. But if the file is bit enough like my situation, you could just pipe this command to write it to a file like so:

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git cat-file -p cf70ac7b | out-file temp.js

If you’re using linux or Mac, just use your version of the equivalent.

And that’s it, repeat this until you have all of the files you need.

Summary

A few lessons I learnt from this accident:

Always check you have added all your files before committing (I know it sounds obvious, but it could happen to you the way it happened to me).
Always make sure you commit your changes often after each set of critical change.
This one has become my preference now. Rebase from your local branch and not upstream:

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git add .

git commit -m "Your awesome and informative commit message"

git checkout master

git pull

git checkout feature-branch

git rebase master

And if you lost your code, don’t give up, git is a really powerful tool.

Hope this helps someone to save some time in case of a similar accident.

Stop using `console.log`, start using your DevTools 🛠️

Thu, 19 Mar 2020 00:00:00 GMT

There are many situations where we want to see what’s wrong with out code without the trouble of changing source code and push the changes again, regardless of whether we’re using local environment or production. Most folks start by writing console.log statements throughout their code base and go step by step to find the place where the bug is happening. That’s OK for beginners and where you have access to source code, but what if you don’t want to waste so much time or you don’t even have access to source code?

DevTools

All major browsers have developer tools (aka DevTools) nowadays. It’s important for us web developers to know them well not just because we use them as our daily drivers to test our applications and see how they look like once deployed, but also for times when something is wrong as we want to find them efficiently.

That’s when the DevTools comes very handy if you know the ropes. DevTools have a lot of functionalities; refer to my articles Chrome DevTools can do that? and FireFox DevTools can do that? to have a glimpse of some of these. However, in this article we only focus on debugging experience.

The bug

In order to be able to have a common ground, we need a bug to fix. I’ve created this demo which will be working on in Glitch. In this demo, you would select a date and press the calculate age button. It will calculate your age and show it in the bottom section.

However, there is a bug where sometimes it calculates the age by one year higher than actual. We will be looking into how to fix this.

DevTools’s debugger

Both Chrome and Firefox have a debugger section we will be using in this article. I won’t go through Edge because it’s the same as Chrome.

Chrome

You can open your DevTools in Chrome using Ctrl+Shift+J on Windows or Ctrl+Option+J.

Once opened, navigate to the Sources tab. You will see a file navigator pane on the left where you can inspect the files that the page uses. Then there is the editor pane in the middle where you can click on the file from the navigator pane and see the content and edit them locally in the browser. And last you will see the JavaScript debugging pane where you have a set of features which you’ll learn about shortly.

💡 If you resize the DevTools you might see these panes in different positions.

Firefox

In Firefox you need to use Ctrl+Shift+I on Windows or Ctrl+Option+I to open up the web developer tools.

When opened, click on debugger tab which is very similar to what you saw before. On the left, you’ll see the navigation pane, next to it is editor pane and to the left (or below depending on how wide you’ve got your DevTools open) is the debug pane.

Setting a breakpoint

When it comes to debugging, a common method is to use console.log statements throughout the code base which sometimes is abused.

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const yo = document.querySelector('#yo');

function getAge() {
    console.log('Getting the date of birth value');
    const dateString = document.querySelector('#age').value;
    console.log(`date of birth is ${dateString}`);
    var today = new Date();
    var birthDate = new Date(dateString);
    var age = today.getFullYear() - birthDate.getFullYear();
    console.log(`age is ${age}`);
    var m = today.getMonth() - birthDate.getMonth();
    console.log(`Birth month is ${m}`);
    if (m < 0 || (m = 0 && today.getDate() < birthDate.getDate())) {
      console.log('The birth month is negative or is zero, we need to reduce the age by one year');
      age--;
      console.log(`Real age is ${age}`);
    }
   yo.textContent = age;
}

And then you look at the console to see where the bug might be. But this process is painstakingly slow which impacts your productivity a lot. So let’s see how breakpoints help us get to the point real quick.

Breakpoints have the advantage of being in real time compared to console.log statements where you need to wait for the code to get deployed and inspect the console. Apart from that, with console.log statements, you need to explicitly mention which values you want to expect whereas in a breakpoint debugger shows you all of them.

Now let’s take one step back and see how we can go about finding where to set our breakpoint to. In some cases like this you will think OK, the age is correct sometimes and not others depending on the month. So you can find your file and set your breakpoint right where the if condition is.

In some other cases where the code base might be larger, or you might be new to the team, it makes sense to follow the flow of the page. In our case user selects a date and then clicks on the calculate age button.

The logic behind happens under that click, you the best thing for us is to set a breakpoint on the click event listener. Event Listener Breakpoints are designed for this.

Chrome

In Chrome, in the debug page, click on the Event Listener Breakpoints and expand the section. Then find the Mouse category and select the click event.

Now click on the calculate age button and DevTools will pause when the event listener executes. You might need to click on the Resume Script Execution if you’re using a platform like Glitch, but for your own app that won’t be needed. When the breakpoint reaches the button in your HTML, press Step into function and you’ll end up in our getAge function. Once you’ve stepped into the function you wanted, you can go one line at a time by clicking on the step over button or pressing F10.

Firefox

You can use the same approach to enable a mouse click event listener breakpoint in Firefox, simply expand the Event Listener Breakpoints section in the debugger pane, then expand Mouse and select the click event.

Once enables, you could follow the same procedure we described before. First click on the calculate age button and the debugger automatically pauses on the first function call. In case of using a platform like Glitch or CodePen, that might not be what you’re after, so simply press the Resume button until you see the breakpoint stop at the getAge function. Then click on the Step In button or press F11 to go inside the function. Once you’re inside the function simply press Step over button or F11 to go line by line from thereon.

Line breakpoint

Line breakpoints are mainly used when you’ve narrowed down where the bug might actually be. In our case when we stepped through the getAge function, we saw that the age is calculated based on the year, then there is an if condition which will be responsible to reduce the age by one if the month is less than the current month minus the month of birth.

So we roughly know that if the age is calculated right in some cases and wrong by one year in others, the if condition is where we should set our line breakpoint on.

There are two ways to do this in DevTools, one is to follow the event listener breakpoint flow explained above. But if you know the filename beforehand, you can simply open the file in the editor pane and scroll through until you reach the line you want.

Once you’re there, simply click the line number and it will put a Line Breakpoint icon on that line so that you’d know where the breakpoint is set. You can remove the breakpoint by simply clicking on it again.

Now if you click the calculate age button, the program stops on the if condition. This part is exactly the same in both Chrome and Firefox.

Checking variable values

When you’re stopped at the if condition, if you want to see what is the value of a variable, simply have a look at the debugger pane’s Scope section in Chrome or Scopes section in Firefox.

Chrome

Firefox

Spotting the bug

Now let’s see where the bug is and how to fix it. If you have a look at the if condition more closely, you’ll see that there are two main parts in there. First one is m < 0 to check whether the month is less than zero, and the second is m = 0 && today.getDate() < birthDate.getDate() to check if the month is zero and today is less than birthday.

Now we know that someone’s used an equal sign instead of equality operator which has caused this bug. So let’s replace the = with === and then press Ctrl+S to save the changes. You can leave the breakpoint or remove it test with some dates to see if the bug is fixed or not. But after some tests we know that the bug is fixed. It’s time for you to go and write a test for this function so you won’t face the same bug again 😁.

Console window

Don’t forget that you can evaluate your expressions in the console window of the browser. As in you could simply put your condition in the console and see whether it’s returning true or false.

What else?

There are heaps of other breakpoints you could use such as conditional breakpoints which are triggered only if a condition you provide is true, breakpoints on caught and uncaught exceptions, and XHR breakpoints which are triggered when a URL matches a substring you’ve set. Let’s try a XHR breakpoint in , open up your DevTools, head over to debug pane and open the XHR Breakpoints section. Click in the box to add a line and enter raw and press Enter. Now refresh the page and you’ll see the breakpoint hit when the request is made. You can now use the same technique we saw earlier to step in the code and set a like breakpoint to debug further.

Small catch

One catch is that you need to make sure that the function you’re debugging is in the scope which is tricky if you’re using DevTools. In order to get it working you need to set a line breakpoint somewhere where the function is in scope, then trigger the breakpoint and call debug() in the DevTools console while the code is still paused on the line breakpoint.

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(function () {
  function hello() {
    console.log('hello');
  }
  function world() {
    console.log(' world');
  }
  hello(yo); // This works.
  world();
})();
debug(hello); // This doesn't work. hey() is out of scope.

Summary

We saw how powerful the DevTools are and how much they can help us to find and fix bugs in our code. So stop using console.log and get to know your DevTools better. Happy coding from home ❤️.

What you need to know about Full screen API 💻

Tue, 10 Mar 2020 00:00:00 GMT

There are many situations where we’d like to see our web page in fullscreen mode. Be it games, online courses, video tutorials, or simply wanting more reading space while reading a book. What we usually do in these sort of scenarios is we manually set our browser’s tab/window in fullscreen mode (F11), but the result is not always what we expect, because some content is not designed to be viewed in fullscreen mode. Besides, what if we help our users to go fullscreen automatically instead, again it all comes to having a better user experience.

Intro

Full Screen API adds methods to the HTML Element to enable us to programmatically turn any content on a page to enter in fullscreen mode via JavaScript. WebGL, canvas, and video elements are the usual targets when it comes to going fullscreen. Online newspapers and magazines are other areas where this can be helpful.

So let’s see this in action first and then go through some details:

See the Pen Full Screen API Demo by Yaser Adel Mehraban (@yashints) on CodePen.

All we’re doing here is to call a method which is added by the Full Screen API:

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const vid = document.getElementById('shuttle');

function toggleFullScreen() {
  if (!document.fullscreenElement && vid.requestFullscreen) {
    vid.requestFullscreen();
  } else {
    if (document.exitFullscreen) {
      document.exitFullscreen(); 
    }
  }
}

document.addEventListener("keydown", function(e) {
  if (e.keyCode == 13) {
    toggleFullScreen();
  }
}, false);

Exposed properties

There are two properties exposed on the document object:

💡 DocumentOrShadowRoot.fullscreenElement

The fullscreenElement property will give you the element that is displayed in fullscreen mode at the moment. It’s a way to check whether we’re in full screen mode or not.

💡 Document.fullscreenEnabled

The fullscreenEnabled property tells you whether or not the document is currently in a state that would allow fullscreen mode to be requested.

Exiting fullscreen

You’ll want to be sure to let your users know that they can press the Esc key (or F11) to exit fullscreen mode.

In addition, navigating to another page, changing tabs, or switching to another application (using, for example, Alt-Tab) while in fullscreen mode exits fullscreen mode as well.

As you saw in the example above, exiting the fullscreen mode can be done using document.exitFullscreen:

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if (document.exitFullscreen) {
  document.exitFullscreen(); 
}

Feature detection

You can simply detect whether the feature is supported or not using either document.requestFullscreen or Element.requestFullscreen:

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if(element.requestFullscreen) {
  element.requestFullscreen();
}

or:

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if(document.requestFullscreen) {
  // enter fullscreen mode
}

Finding whether or not you’re in fullscreen mode

As mentioned earlier, the document.fullscreenElement is a good way to check whether the browser is in full screen mode or not. The value of this property will be null if we’re not in fullscreen, and the current fullscreen element otherwise.

⚠️ There is also a boolean property called fullscreen which is deprecated and should not be used. Although most of the browsers still support it.

Presentation

When toggling fullscreen mode programmatically, you’re responsible for how the elements will look like and what appears on the screen. It’s obvious you will need to change the width and height of the element to %100, and fortunately, there is a CSS pseudo-selector for you to use:

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#shuttle:fullscreen {
  width: 100%;
  height: 100%;
}

Also you might want to hide some other elements on the screen to reduce clutter:

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:fullscreen .hide {
  display: none;
}

Browser support

The browser support is really good at this point, almost all major browsers fully support it. Only IE11 and Safari have partial support. Opera mini and Android Browser do not support it at this point.

Hope you’ve learned a new trick if you didn’t know about this API and happy fullscreening (just made up the word 😁).

Stop gobbling up that memory 🛑

Fri, 28 Feb 2020 00:00:00 GMT

I’ve been writing web applications for more than a decade. From classic ASP to PHP, ASP.Net web forms and the list goes on and on. However, something that’s been common between all those years for me has been to care about how performing the site is. One important part of that has been to look out for memory leaks, because they can cause the page to go super slow or even crashing in more serious scenarios.

Intro

Memory leaks are a common problem in software development, regardless of whether the language you’re using is memory managed or not. By that I mean languages which come with a garbage collector. Memory leaks happen when a piece of memory is allocated, but never freed by the application, and is not returned to the container app or the operating system.

I remember going through the concept in uni, but I can’t remember anything apart from the fact that usually there is a tree made up of all the occupied memory locations. Every time the garbage collector is looking into the memory parses that tree, and if a node is not connected to any branch, it gets recollected and returned to the main program.

Most of us web developers are likely to use one of the major frameworks or libraries to write our applications. Some maybe using a bit older languages like PHP or Ruby, but no matter what we use, there will be a high chance that we come face to face with this problem one way or another.

Consequences

So what happens when there is a memory leak in our applications 🤔?

In some cases the memory consumption just keeps going up. If the user is using a decent spec machine, they might not even realise it. Not everyone is obsessed like us developers checking their task manager often to see how much memory is consumed.

Regardless, it slows down the page, makes interactions not responsive, and might even cause the tab or the whole window to crash.

Memory leak in JavaScript

It’s way easy in JavaScript to allocate some memory and forget about it. Even if you’re not writing plain JavaScript, it’s still possible that a memory leak happen, without you noticing it.

But how does it happen?

In JavaScript there are a few possible ways a memory leak can happen.

Unintentionally creating global variables
Timers and callbacks
Out of DOM references
Closures
Event listeners

Global variables

It’s very simple to create an unwanted global variable in JavaScript. Consider below code:

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function helloWorld() {
  name = 'Yas';
  console.log(`Hello ${name}`);
}

In this simple function we have created a global variable called name. We didn’t want to, but we did it anyway.

💡 A reference to an undeclared variable creates a new variable inside the global object.

Same thing can happen if you use this:

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function helloWorld(args) {
  this.name = 'Yas';
  console.log(`Hello ${name}`);
}

To prevent these sorts of leaks, use JavaScript in strict mode. You can do it by adding use strinct; at the top of your JavaScript file.

Even thought we consider accidental global variables one of the memory leak sources, there are still many global variables defined by the framework we use, or even the ones we intend to be there. Remember these are non collectable variables and unless nulled or reassigned, garbage collectors can’t do anything about them.

Timers and callbacks

The use of setInternal and setTimeout has gotten less and less popular as we’ve moved towards more modern concepts like async/await. Furthermore, some libraries and frameworks provide observables to facilitate callbacks. In which case they’re responsible for making sure the callbacks are unreachable once their own instance gets destroyed.

However, there are quite a number of scenarios where we need to use it in order to call a function at a later time or on a schedule.

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let data = fetchData();
setInternal(function() {
  let node = document.querySelector('#list');
  // loop through data and create the html
  node.innerHTML = transform(data);
}, 1000)

This example shows how a timer can turn into something that cannot be collected. Even if the list node is removed from the DOM, the reference inside the handler remains active and cannot be collected. That causes their dependencies to be non collectable as well. So the data variable which might be really large, would sit in memory long after its need has ended.

Now let’s see how we can improve this to avoid a memory leak:

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let node = document.querySelector('#list');
let data = fetchData();

function handler(data) {
  if(node) {
    // do stuff with data and create the list
    node.innerHTML = transform(data);
  }
};

setInterval(handler, 1000);

Out of DOM references (detached DOM)

When some nodes are removed from the DOM but still exists in memory through JavaScript, we have out of DOM references or detached DOM. Usually it means there is a reference to a variable which was referencing that node.

DOM is a doubly linked tree, meaning any reference to any node would mean the entire tree would not be garbage collected.

Let’s go through an example to make this a bit more clear:

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function create() {
  let ul = document.createElement('ul');
  ul.id = 'list';
  for (var i = 0; i < 10; i++) {
    var li = document.createElement('li');
    li.textContent = `Item # ${i}`;
    ul.appendChild(li);
  }
  return ul;
}

const list = create();

document.body.appendChild(list);

function deleteList() {
  document.body.removeChild(document.getElementById('list'));
}

document.getElementById('delete').addEventListener('click', deleteList);

Clicking the delete button, will remove the list from the DOM, but there is a reference in JavaScript, so the list never gets garbage collected. We could identify detached node using heap snapshots in your browser DevTools. I am using Chrome here, but you can use Edge (similar to Chrome), and Firefox too.

And once the snapshot is taken, type detached in the filter text box and you’ll see the detached DOM nodes.

The way to fix these kind of issues is to always use local variables so that the reference is destroyed once the function execution is done.

Closures

Closures are one of the JavaScript’s features where most beginners struggle with. But once you’ve got it, it’s really easy to follow. In it’s core, a closure gives you access to an outer function’s scope from an inner function.

A more technical definition is that a closure is a combination of a function bundled together with references to it’s surrounding state (the lexical environment).

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function init() {
  var hello = 'Hello'; // hello is a local variable created by init
  function helloWorld() { // helloWorld() is the inner function, a closure
    console.log(`${hello} world!`); // use variable declared in the parent function
  }
  helloWorld();
}
init();

Now that we know what’s a closure, let’s see how they can cause memory leaks. Imagine the following code:

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var newElem;
 
function outer() {
    var someText = new Array(1000000);
    var elem = newElem;

    function inner() {
        if (elem) return someText;
    }

    return function () {};
}

setInterval(function () {
    newElem = outer();
}, 5);

In the above code, the inner function is never called, but it holds a reference to the elem. Keep in mind the scope of the inner is the same as function () {} which is returned by the outer function. Since newElem is a global variable, as long as a reference is pointing to function () {}, the shared context is preserved and someText is kept. Each call will then result in a remaining reference and as time goes by, we run out of memory eventually.

So what we can we do about these type of scenarios? First we need to stop using var. And furthermore, if we call the inner function like outer()(), then there won’t be any references left.

Event listeners

Every time you attach an event handler to a specific element, you need to keep a reference and remove it when you’re finished. So instead of:

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function deleteList() {}

document.getElementById('delete').addEventListener('click', deleteList);

We should be doing:

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function deleteList() {}

document.getElementById('delete').addEventListener('click', deleteList);

// do stuff

document.getElementById('delete').removeEventListener('click', deleteList);

Summary

We saw what will cause a potential memory leak in JavaScript and how to fix those issues, however, keep in mind that in most cases if you’re using a framework or library, these things are handled for you. If you’re using a library which you might suspect is causing memory leaks, you could easily find out using your browser DevTools memory profiler.

Hope this article has raised some awareness so that you can write more performing code and make user experience much better. No one wants to have their browser chew up memory like cheesecake right 😁?

Resources

More about Chrome DevTools memory profiler.
Find out about Firefox DevTools memory profiling.

Run code analysis with sonarqube using docker

Sun, 23 Feb 2020 00:00:00 GMT

I help some of my friends perform code reviews on their code bases from time to time as a side activity. I’ve used codelyzer before and it’s very similar to tslint in a sense. However, I wanted to test something new and thought let’s give SonarQube a shot this time.

Intro

SonarQube® is an automatic code review tool to detect bugs, vulnerabilities and code smells in your code. It can integrate with your existing workflow to enable continuous code inspection across your project branches and pull requests.

It has a server component where you can create projects and apply configurations like adding plugins and updating existing ones. And then there is a scanner component where it scans your code base and sends the result to the server to show in the SonarQube dashboard.

There are multiple versions of SonarQube but we’re going to use the community edition which is free and open source.

So without further ado, let’s get to it.

Setup

The documentation is really great, and there is a great two minute get started which is what I used to get my hand wet real quick. However, soon I realised that I have to install a lot of dependencies to get it working.

I was thinking how to avoid the extra installations, when suddenly a smile came to my face when I saw there is a docker image as well.

On the Docker Hub, you can find the information you need to get started, but for the purpose of this article, I just use a single command to get it going.

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docker run -d --name sonarqube -p 9000:9000 sonarqube

This command will pull the image down and create a container from it. Run the container in the background mode and then exposes the port 9000 through to host.

Once done, you need to wait for a few mistunes for the server to get started. You can open a browser of your choice and go to localhost:9000 to see the server dashboard.

Use the default username as admin and the password admin to login.

Create a project

I don’t want to go deep into SonarQube here, but a project represents a code base where you can see the result of a scan done by the scanner. So once logged in, click on create a new project button in the centre of the page, then enter a unique project key and a display name.

On the next page enter a name for your project token. This is the key which scanner will use to authenticate to the server and send the result of a scan up.

Take note of this key as you can never see it once you’re navigated away from this page. Click continue and you’ll see a screen where you can specify your project configuration.

I wanted to run this on an Angular project with TypeScript, so I chose other, and then windows from the OS prompt.

Downloading the scanner

At this point you need to download the scanner and unzip it in a folder named sonarqube on your drive. I usually use c:\tools for these sort of usage (replace this with what you used if you chose to unzip it elsewhere).

Once done, open your scanner config file named sonar-scanner.properties from c:\tools\sonarqube\config folder and uncomment the line which specifies the server address.

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#Configure here general information about the environment, such as SonarQube server connection details for example
#No information about specific project should appear here

#----- Default SonarQube server
sonar.host.url=http://localhost:9000

#----- Default source code encoding
sonar.sourceEncoding=UTF-8

Running a scan

Once done, you’re ready to go. Run the command below from your project root and wait for the scan to finish.

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C:\tools\sonar\bin\sonar-scanner.bat -D"sonar.projectKey=fp" -D"sonar.sources=." -D"sonar.host.url=http://localhost:9000" -D"sonar.login=**********************************" -D"sonar.exclusions=node_modules/**/*"

Don’t forget to replace the key you got from the previous step in the sonar.login argument.

💡 In the last step when you downloaded the scanner zip file, the command you need to execute is written down for you ready to go, just add the exclude folder to avoid code analysis on external libraries.

It takes a while for the scan to finish based on the size of your code base. But once done, you can see the result in the SonarQube dashboard.

ℹ️ Remember to run npm install or yarn if you’ve just forked the code base from your git repository. I faced a few errors before I realised I didn’t have those installed and they are used by the scanner.

And once done, here is yow your dashboard will look like. Obviously the code base I was reviewing was a bit chaotic.

And you when you click on issues you can see them by category and also the rules used to perform the scan.

Summary

In terms of the speed, I was very happy with the result. It took nearly 2 minutes to scan my entire code base with more than 520 files and thousands line of code.

In term of the scan result, I would say based on the default rule set and considering that this was the community edition, the results are slightly better than tslint or codelyzer. I could easily navigate through issues, find out what line of code needed attention. It showed me the results with syntax highlighting and a lo of categories and tags where I could drill down and find what I wanted quickly.

So go ahead and give it a shot, I am sure you’ll find enough to keep you busy for a while to fix those. And bare in mind that it not only gives you linting errors, it will also give you some security hints based on OWASP top 10 as well.

Retro HTML, let's create marquees 😃

Sun, 09 Feb 2020 00:00:00 GMT

One of the first things I learnt to do with HTML was using marquee to move text across the screen horizontally. It was so cool to be able to create advertisements on a page and make users notice things with just a tag. Of course people overused it and then it became a out of fashion item in the new designs just like baggy jeans from 90s.

History

The HTML <marquee> element was used to insert a scrolling area of text. You could control what happened when the text reached the edge of it’s area using its attribute. Of course when I use past tense it doesn’t mean it’s not supported anymore. It became obsolete a while back, but most browsers still support it.

You can see it in action:

See the Pen Marquee by Yaser Adel Mehraban (@yashints) on CodePen.

CSS marquees

So I want to simulate some of these with just CSS. We’ll be using CSS animations and play with overflow to simulate text reaching to the edge.

Scrolling text

So let’s play with translateX() to specify the content placement at the start and end of the animation. We’ll use this to keep the text moving between start and end.

For the animation we will use an infinite linear with 10 seconds duration.

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.marquee {
  height: 50px;
  overflow: hidden;
  position: relative;
}
.marquee span {
  font-size: 2em;
  color: turquoise;
  position: absolute;
  width: 100%;
  height: 100%;
  margin: 0;
  line-height: 50px;
  text-align: center;
  transform:translateX(100%);
  animation: cssmarquee 10s linear infinite;
}
@keyframes cssmarquee {
  0% {
  transform: translateX(100%);
  }
  100% {
  transform: translateX(-100%);
  }
}

And the HTML is simple:

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<div class="marquee">
  <span>Scrolling Text </span>
</div>

See the Pen CSS-Marquee-ScrollText by Yaser Adel Mehraban (@yashints) on CodePen.

Slide in

Now let’s slide in the text and fix it at the beginning. We’ll use ease-out with a 200% value for translateX start and 0% for the end.

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.marquee {
  height: 50px;
  overflow: hidden;
  position: relative;
}
.marquee span {
  font-size: 2em;
  color: green;
  position: absolute;
  width: 100%;
  height: 100%;
  margin: 0;
  line-height: 50px;
  text-align: left;
  animation: cssmarquee 10s ease-out;
}
@keyframes cssmarquee {
  0% {
    transform: translateX(200%);
  }
  100% {
    transform: translateX(0%);
  }
}

I won’t repeat the HTML code again to save some typing 😁. It’s exactly as above.

See the Pen CSS-Marquee-SlineIn by Yaser Adel Mehraban (@yashints) on CodePen.

Left to right

Now let’s move the text from left to right this time. Again, we’ll use a linear infinite animation with the reverse values for translateX as our first example.

The only other difference will be the initial value for transform property.

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.marquee {
  height: 50px;
  overflow: hidden;
  position: relative;
}
.marquee span {
  font-size: 2em;
  position: absolute;
  width: 100%;
  height: 100%;
  color: green;
  margin: 0;
  line-height: 50px;
  text-align: center;
  /* Starting position */
  transform: translateX(-100%);
  animation: cssmarquee 20s linear infinite;
}
@keyframes cssmarquee {
  0% {
    transform: translateX(-100%);
  }
  100% {
    transform: translateX(100%);
  }
}

See the Pen CSS-Marquee-L2R by Yaser Adel Mehraban (@yashints) on CodePen.

Scroll vertically

By now you should be comfortable guessing what will be using. Instead of translateX, we will be using translateY.

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.marquee {
  height: 100px;
  overflow: hidden;
  position: relative;
}
.marquee span {
  font-size: 2em;
  position: absolute;
  color: green;
  width: 100%;
  height: 100%;
  margin: 0;
  line-height: 50px;
  text-align: center;
  transform: translateY(-100%);
  animation: cssmarquee 5s linear infinite;
}
@keyframes cssmarquee {
  0% {
    transform: translateY(-100%);
  }
  100% {
    transform: translateY(100%);
  }
}

See the Pen CSS-Marquee-Down by Yaser Adel Mehraban (@yashints) on CodePen.

Bouncing text

Now let’s assume back then people wanted to get fancy. We want to bounce the text this time 😃. We will need to add alternate to our animation and reduce the delay. We will also add trnslateX so that the content doesn’t bounce off the whole page.

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.marquee {
  height: 200px;
  overflow: hidden;
  position: relative;
}
.marquee span {
  font-size: 2em;
  position: absolute;
  color: turquoise;
  width: 100%;
  height: 100%;
  margin: 0;
  line-height: 50px;
  text-align: center;
  transform: translateY(70%);
  animation: cssmarquee 1s linear infinite alternate;
}
@keyframes cssmarquee {
  0% {
    transform: translateY(70%);
  }
  100% {
    transform: translateY(0%);
  }
}

See the Pen CSS-Marquee-Bounce by Yaser Adel Mehraban (@yashints) on CodePen.

Typewriting effect

Now this time we want to mix our animation with a bit of stepping to create a typewriter effect. We will be using from and to for our keyframes. Then use steps and step-end to simulate the text and blink cursor effect.

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body {
  font-family: 'Special Elite', cursive;
  background: #efefef;
  padding-top: 5em;
  display: flex;
  justify-content: center;
}

.typewriter h1 {
  overflow: hidden; 
  border-right: .15em solid green; 
  white-space: nowrap;
  margin: 0 auto; 
  letter-spacing: .15em; 
  animation: 
    type 4s steps(50, end),
    blink-cursor .7s step-end infinite;
}

@keyframes type {
  from { width: 0 }
  to { width: 100% }
}

@keyframes blink-cursor {
  from, to { border-color: transparent }
  50% { border-color: green; }
}

Don’t forget to add the Special Elite font from Google fonts.

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<head>
  <link href="https://fonts.googleapis.com/css?family=Special+Elite&display=swap" rel="stylesheet">
</head>

See the Pen CSS-Marquee-TypeWriter by Yaser Adel Mehraban (@yashints) on CodePen.

Summary

That was it. You can go back to whatever important job you were doing. A bit of distraction is always good for me and hope this bit was good for you too 😊. Until next time 👋🏼.