DEV Community: Sourabh Singh

Working Of Compiler In JavaScript

Sourabh Singh — Sun, 19 Mar 2023 14:27:15 +0000

JavaScript falls under the general category of "dynamic" or "interpreted" languages. But it is often misunderstood, in-fact JavaScript is Interpreted as well as Compiled language. Let's understand more about the execution of JavaScript code in the Blog

Working of Compiler in JavaScript

In traditional compilation process of a language, a chunk of source code undergo typically three steps before execution.

Tokenizing / Lexing
Parsing
Code Generation

Tokenizing / Lexing:

Breaking up a Sting of characters into meaningful chunks called tokens.

Parsing:

A Stream (array) of tokens are turned into a tree of nested elements, which collectively represents the grammar structure of the program. This tree is called "AST" (Abstract Syntax Tree).

Code Generation:

The process of taking an AST & turning it into executable code.

But, the JavaScript Engine is vastly more complex than just these steps. Any Java-Script code is compiled even before it is executed.

Note: Execution of JavaScript Code is done by Interpreter.

Compilation before execution:

JavaScript compiles all the declarations & Assignments before the code is sent for execution so that the interpreter can skip those lines. This is done for faster execution speed.

let a = 3;    //The declaration and assignment of variable 
                will be compiled before execution.
console.log(a)  //This part will be executed by JavaScript 
                  interpreter

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HOW TO USE JAVASCRIPT IN YOUR IDE WITHOUT BROWSER

Sourabh Singh — Sun, 22 Jan 2023 07:09:27 +0000

JavaScript in IDE

Some time ago it was not possible to use JavaScript without a web browser but, now with the help of Node.js it is possible to use JavaScript inside any IDE or code editor without touching your Web Browser.

Node.js and JavaScript

In order to use JavaScript in your code editor or IDE we have to initialise a npm package which can be done by following command in your terminal.

npm init

After executing this command you will be prompted several questions in your terminal where you have to press enter after specifying the answer.

Note:
You can leave the prompt empty and press enter. The terminal will feed the default value as input.

Doing so will initialise a package.json file in your folder. which will have all the necessary details of the your package.

Using Node.js Packages

In order to use various Node.js Packages you will need to install them first with the following command:

With NPM

npm install <package-name> --save

With Yarn

yarn add <package-name>

After this you need to declare the packages inside your JS file to access all it's features.

For Example let us use the prompt-sync package inside our JS file:
1.Installing the package with Node Package Manager (npm)

npm install prompt-sync --save

2.Declaring a variable to use package's properties

const prompt = require("prompt-sync")();
let name = prompt("Enter Your Name");
console.log(name)

Notes:

require fetches the package from node modules.
prompt takes input from user.
console.log(name) prints the entered value.

Congrats !! you've learnt how to use JavaScript without browser inside your favourite code editor or IDE.

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JavaScript as your first programming language

Sourabh Singh — Sun, 15 Jan 2023 08:02:59 +0000

If you are a beginner in programming and you don't know where to start from then JavaScript is "THE LANGUAGE" for you.

WHAT IS JAVASCRIPT ?

If we go to the formal definition of JavaScript provided by MDN-Web-Docs JavaScript (JS) is a lightweight, interpreted, or just-in-time compiled programming language with first-class functions.
Many beginners think that JavaScript is only useful for developing web-pages but they are wrong. I'll explain how further in this blog.

WHY JAVASCRIPT ?

JavaScript came into existence around 27 years ago, and since then it has gone through number of improvements. And according to a survey done by GitHub JavaScript has been #1 choice for developers since years.

photo taken from octoverse.github.com

If you asked me the same question that which programming language to start with 10-13 years ago, before the existence of Node.js, I must've given a different answer but the improvements that JavaScript got after the entry of Node.js changed my mind completely.

JAVASCRIPT vs. OTHER LANGUAGES 🔥🔥

After the entry of Node.js JavaScript has became very much powerful. Now you can perform any kind of task that any other programming language ( say C, C++, Java, Python) can do. And it also has a large amount of additional features that other languages are not able to perform that easily.

Node.js made JavaScript usable even outside the browsers hence made it possible to perform some of the complex tasks like Machine Learning and DSA easier to perform in JavaScript.

POWER OF JAVASCRIPT 💪🏻

At current stage JavaScript is capable of performing various complex tasks very easily as compared to other languages.
THE FLEXIBILITY OF JAVASCRIPT
JavaScript can perform all the following tasks very well.

Web Development
Application Development (IOS & Android)
Computer Application Development(for Windows, MacOS and Linux)
Machine Learning (see TensorFlow.js)
VR & AR Development (see Three.js, AR.js)

This must've explained that JavaScript is way more powerful than just creating web pages 😄

BENEFITS OF LEARNING JAVASCRIPT

Following are some of the major benefits of learning JavaScript

If you are learning JavaScript then you don't need to learn any other language for any other purpose.
You can learn and create bigger projects at the same time.
There is a very huge demand in the tech industry for JavaScript developers and the supply is very sort so it will bring great opportunities to you.
JavaScript has a huge community of experienced and passionate programmers which means a huge support
JavaScript will further improve with time and it will become more powerful

RESOURCES TO LEARN JAVASCRIPT

There are various free and paid resources to learn JavaScript both online and offline.
FREE ONLINE COURSES TO LEARN JAVASCRIPT

Must Consider: You Don't Know JS series by Kyle Simpson

Offline Books : oreilly.com
Online Articles: GitHub

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