What is a Decorator?

A decorator is simply a way of wrapping a function with another function to extend its existing capabilities. You “decorate” your existing code by wrapping it with another piece of code. This concept will not be new to those who are familiar with functional composition or higher-order functions.

With the introduction of Classes in TypeScript and ES6, there now exist certain scenarios that require additional features to support annotating or modifying classes and class members. Decorators provide a way to add both annotations and a meta-programming syntax for class declarations and members.

Why Use a Decorator?

Decorators allow you to write cleaner code and…


Prerequisites:

Basic understanding of Typescript.

What are Generics/ Generic Types?

→ Generics pass some extra information that TypeScript fails to infer (i.e. guess). They allow you to continue working with data in TypeScript optimal way.

→ A generic is a type followed by another type.

For example, there is a variable of type array. Now array can hold data of any type i.e. string, number, etc.

→ It specifies the TS which type of data type it will hold, we can use it.

TRICK: Anything type written inside <> is generics.

A. Some built-in Generics:

  1. Array: If we know the array will hold a specific type (say string).

Here array…


What is a singleton?

Singleton is, at its core, a design pattern that restricts the instantiation of a class to one object. Usually, the goal is to manage the global application state. Some examples using a singleton as the source of config settings for a web app, on the client-side for anything initiated with an API key (you usually don’t want to risk sending multiple analytics tracking calls, for example), and to store data in memory in a client-side web application (e.g. stores in Flux).

A singleton should be immutable by the consuming code, and there should be no danger of instantiating more than…


A. Basics:

  1. Proxy API helps in meta programming like Reflect API or Symbols.
  2. Meta-programming means that you’re able to change (parts of) the behaviour of the underlying language — JavaScript in this case. This of course is a powerful feature as it allows you to influence the way your code is executed.
  3. Suppose there is an object with some properties in it. A source code wants to access it

— in regular case directly access


Why ES6 — Reflect API is important? Let us understand it.

What is the Reflect API?

The Reflect API could be described as a collection or “central place” which houses all kind of object and function related functions (for creation, property management etc.). Some of the functionalities added on the Reflect object where available before on the Object object.

But the goal for the future is, to have on central place to store all those methods — the Reflect Object/ API.
Therefore, the Reflect API provides useful methods to create, manipulate and query objects and functions in your JavaScript project.

Some points to note:

  1. Reflect API deals with Meta programming.

Metaprogramming…


In JavaScript, developers often spend a lot of time deciding the correct data structure to use.This is because choosing the correct data structure can make it easier to manipulate that data later on, saving time.

We as developers generally use objects or array to store data. With ES6, there are two more ways to save data — Maps and Sets

1. Map

A Map is a key-value collection introduced in ES6. It kind of fills the gap between arrays (no key-value pairs) and objects (key-value pairs but much more complex than a simple collection).

  1. The Map object holds key-value pairs and remembers…


No matter how great we are at programming, sometimes our scripts have errors. They may occur because of our mistakes, an unexpected user input, an erroneous server response, and for a thousand other reasons.But there’s a syntax construct try..catch that allows us to “catch” errors so the script can, instead of dying, do something more reasonable.

eg1

lalala;     
// Error msg:ReferenceError: lalala is not defined - code dies here
// my next codes.
console.log('initiating a service'); // this code will break

with try-catch

try {lalala;} catch(err) {console.log(err.stack);   // this will throw in console}console.log('next codes'); //…

Comparison between prototypal inheritance and classical inheritance on multiple parameters. Is classical inheritance obsolete. How does JavaScript inherit objects. Battle between Java and JavaScript.

These questions have always bothered me. What is the difference between prototypal and classical inheritance? Is prototypal inheritance better than classical? If yes, then why?

Being a JavaScript enthusiast, my answer has always been biased towards prototypal inheritance. Then I did more research on it. And it turns out I was right.

Let’s understand those differences and reasons which makes prototypal inheritance better than classical.

First things first.

What is Prototypal and Classical inheritance?

Simply put…


→ Before deployment, React JS is bundled into a single file and deployed.

→ Bundling is great, but as your app grows, your bundle will grow too. Especially if you are including large third-party libraries. You need to keep an eye on the code you are including in your bundle so that you don’t accidentally make it so large that your app takes a long time to load.

→ When we are having an application, its bundle file keeps on growing. Instead of making a 25 MB file we can split it and divide the bundle size.

→ To avoid…


It’s not just about NODE JS. It is more about how far JavaScript can go?

These are some examples where JavaScript is taking place :

  • Windows and OS X Desktop Applications — Using Electron companies including Slack and Microsoft (Visual Studio Code) have used this Node tool set to create native applications.
  • iPhone and Android Applications — React Native now provides native-quality experiences for significant portions of Facebook’s mobile applications in addition to those of companies like CBS Sports, Vogue, and apparently Walmart in the near future.
  • Internet Of Things (iOT) — Javascript is now finding it’s way into production…

Amir Mustafa

Web Artisan. Human — Engineering

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