Javascript Tutorial
- Javascript

Javascript Tutorial

JavaScript is a well-known programming language that is used in a huge range of web development applications. It is an essential skill for any web developer, and this tutorial will help you understand the basic fundamentals of JavaScript programming.

If you are new to programming or just beginning to learn JavaScript, this tutorial will give you a complete introduction to the language.

In this article, we will cover the basics of JavaScript syntax and structure, control flow, functions, objects, and DOM manipulation.

We will also explore some of the best practices for writing clean and maintainable JavaScript code, as well as some advanced concepts like asynchronous programming and RESTful APIs.

What is JavaScript?

JavaScript is a high-level, dynamic, and interpreted programming language that is frequently used for building interactive websites. It is usually used alongside HTML and CSS to create dynamic web content on the client side as we as on the server side.

JavaScript allows developers to design appealing features like dropdown menus, form validation, and sliders.

Why You Should Learn JavaScript?

As we know web development becoming more advanced every day, and JavaScript plays an important role to create attractive and appealing web pages. JavaScript is a top language for designers and web developers.

It is also used to create web applications and mobile applications. Becoming proficient in JavaScript will open up many job opportunities in the tech industry. Also, major companies including Microsoft, Uber, Google, Netflix, and Meta use JavaScript in their projects.

JavaScript is one of the 3 languages all web developers should learn:

  1. HTML to describe the content of web pages
  2. CSS to define the layout of web pages
  3. JavaScript use to create amazing web pages

JavaScript can be added to HTML files in two forms:

  • Internal JavaScript
  • External JavaScript

Internal JavaScript: We can add JS code to our HTML file by writing the code inside the <script> & </script>. The <script> tag can either be placed inside the <head> or the <body> tag as per the needs.

For example, using JavaScript code inside of HTML code, that script enclosing section can be placed in the body or head of the HTML document.

Run on IDE

The final output will display on the console.

“Welcome to Our  Tech Page”.

External JavaScript: We can make the file with a .js extension and simply put the JS code inside of it. After creating the file, we have to add this file in <script src=”file_name.js”> tag, and this <sctipt> can import inside <head> or <body> tag of the HTML file.

For example, using JavaScript javascript code which is written in a separate file. By importing that .js file in the head section.



<!DOCTYPE html>

<html lang=”en”>




Simple Way to Describe JavaScript


<script src=”main.js”></script>









The final output will display on the console.

“Welcome to Our  Tech Page”.

Key Features of JavaScript

Javascript is a well-known programming language and that makes it a programmer’s first choice. It can be used as a front-end and a backend.

Here are some essential features of JavaScript including:

  • Creating Attractive Websites: JavaScript is used to make web pages dynamic and appealing. With the help of JavaScript, we can change the web page content and styles in a dynamic way.
  • Web Servers: Using JavaScript, we can make robust server applications. To be detailed we use JavaScript frameworks like Node.js and Express.js to build these servers.
  • Creating Applications: JavaScript is used to build web and various types of mobile applications. To use JavaScript frameworks like ReactJS, React Native, and Node.js, we can create web and mobile applications.
  • Game Development: We can use it to design Browser games. In JavaScript, lots of game engines are available that offer frameworks for creating games.

How JavaScript Makes HTML Build-Website Better

  • JavaScript is an advanced programming language that makes web pages more amazing and dynamic on the other hand, HTML is a standard markup language that delivers the primary structure of a website.
  • JavaScript adds dynamic content to websites to make them look good and HTML works on the look of the website without the interactive effects and all.
  • JavaScript uses the content to build dynamic web pages while HTML pages are static which means your content cannot be changed.
  • JavaScript does not offer cross-browser compatibility while HTML offers cross-browser compatibility.
  • JavaScript can be implanted inside HTML but you can not HTML be embedded inside JavaScript code.

Essential Things that Make JavaScript Demanding

There are many reasons to become the most demanding of JavaScript. Below is a listing of a few important points:

  • No need for Compilers: JavaScript is an interpreted language, thus it does not require any compiler for compilation.
  • Build a Complete Solution: As we discussed, JavaScript is used in both client and server-side applications, hence it helps us to make an end-to-end solution to a given specific problem.
  • Used Both Client and Server-Side: Earlier JavaScript was used to create client-side applications only but with the development of its frameworks i.e. Node.js and Express.js, it is now used for developing server-side applications too.
  • Used Everywhere & Anytime: You can use it anywhere, anytime. It can help to develop games,  websites, mobile apps, etc.
  • Huge community support: JavaScript has a huge community of users and mentors who love this language and take its legacy forward.

How does JavaScript work?

JavaScript engines are programs that successfully run JavaScript code. They interpret or compile JavaScript code into machine code that a computer can execute.

Here is an overview of how JavaScript engines work:

  1. Lexical analysis: The engine first takes in the JavaScript code and splits it down into separate tokens. This process is known as tokenization or lexical analysis. The tokens are stored in a data structure called a token stream.
  1. Parsing: The next step is to parse the token stream into an abstract syntax tree (AST). It follows a tree-like structure that represents the syntactic structure of the code. It is used by the engine to analyze and optimize the code.
  1. Compilation: Once the AST is created, the engine develops bytecode, which is an intermediate representation of the code that is more efficient to execute than the original JavaScript code. Some engines also develop machine code directly from the AST.
  1. Optimization: The engine then performs different optimizations on the bytecode or machine code to make it run faster. These optimizations can have inlining functions, clearing dead code, and reordering operations to take advantage of CPU caches.
  1. Execution: Finally, the optimized code is executed on the computer’s processor. As the code runs, the engine monitors its performance and changes the optimization strategy as required.

Some popular JavaScript engines include V8 (used in Google Chrome), SpiderMonkey (used in Mozilla Firefox), and JavaScriptCore (used in Apple Safari). These engines have various approaches to optimizing JavaScript code, but they all follow a similar basic process.

Basic Syntax and Variables in JavaScript

JavaScript code consist of statements that are executed by a web browser. A statement is a single line of code that performs an action.


Variable Explanation Example
String This is a series of text refer as a string. To indicate that the value is a string, enclose it in single or double quote marks. let myVariable = ‘Bob’; or

let myVariable = “Bob”;

Number This is a number. Numbers don’t have quotes around them. let myVariable = 10;
Boolean This is a True/False value. These true and false are special keywords that don’t require quotation marks. let myVariable = true;
Array This is a structure that lets you store numerous values in a single reference. let myVariable = [1, ‘Bob’, ‘Steve’,10];

Refer to every member of the array:

myVariable[0], myVariable[1], etc.

Object This can be anything. Everything in JavaScript refers to an object and it can be stored in a variable. let myVariable = document.querySelector(‘h1’);

All of the above examples too.


Final Thought

JavaScript is a powerful programming language that is essential for web development. In this tutorial, we covered the basics of JavaScript, including variables, functions, features, and control structures.

By understanding these fundamental concepts, you will be able to create dynamic and responsive web applications using JavaScript.

With continued practice and study, you can become a skilled JavaScript programmer and make significant contributions to the web development community.