Javascript: Zero to Hero Course 100% Free | Part - 1

JavaScript Course - Introduction

JavaScript Course

Part 1: Introduction to JavaScript

What is JavaScript?

JavaScript is a high-level, interpreted programming language that conforms to the ECMAScript specification. It is one of the core technologies of the World Wide Web, alongside HTML and CSS. JavaScript enables interactive web pages and is an essential part of web applications. The majority of websites use it, and all major web browsers have a dedicated JavaScript engine to execute it.

Key Features of JavaScript:

  • Interpreted Language: JavaScript code is executed line-by-line without the need for prior compilation.
  • Event-Driven: JavaScript is designed to handle user actions such as clicks, form submissions, and keypresses.
  • Dynamic Typing: Variables in JavaScript can hold values of any data type and can change types dynamically.
  • Prototype-Based Object-Orientation: JavaScript uses prototypes rather than classical inheritance.
  • First-Class Functions: Functions in JavaScript are first-class objects, meaning they can be stored in variables, passed as arguments, and returned from other functions.

Setting Up the Development Environment

To write and run JavaScript, you'll need a few essential tools:

1. Text Editor/IDE:

  • Visual Studio Code: A popular free code editor with a lot of features. Download Visual Studio Code.
  • Other Options: Sublime Text, Atom, or even Notepad++.

2. Web Browser:

  • Google Chrome: Known for its powerful developer tools.
  • Mozilla Firefox: Also includes excellent developer tools.
  • Microsoft Edge: Another good choice with strong development features.

3. Node.js (Optional, for server-side JavaScript):

Node.js allows you to run JavaScript on the server-side. Download Node.js.

Visual Studio Code Installation Steps:

  1. Download from Visual Studio Code and download the installer for your operating system.
  2. Run the installer and follow the prompts to complete the installation.
  3. Install useful extensions like:
    • ESLint: For JavaScript linting.
    • Prettier: For code formatting.
    • Live Server: For running a local server with live reload.

Node.js Installation Steps:

  1. Download from Node.js and download the installer for your operating system.
  2. Run the installer and follow the prompts to complete the installation.
  3. Verify Installation:
    • Open your command line (Command Prompt, PowerShell, or Terminal).
    • Type node -v to check the Node.js version.
    • Type npm -v to check the npm (Node Package Manager) version.

Your First JavaScript Program

Let's create and run a simple JavaScript program.

1. Create an HTML file (index.html):

<!DOCTYPE html>
<html lang="en">
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>JavaScript Course</title>
    <h1>Welcome to JavaScript</h1>
    <script src="script.js"></script>

2. Create a JavaScript file (script.js):

// This is a single-line comment
/* This is a 
   multi-line comment */

// Display a message in the console
console.log('Hello, JavaScript!');

// Display a message on the webpage
document.write('Hello, JavaScript!');

// Display an alert message
alert('Welcome to JavaScript!');

3. Run your program:

Open the index.html file in a web browser. You should see "Hello, JavaScript!" displayed on the webpage, and the same message in the browser’s console. You should also see a pop-up alert with the message "Welcome to JavaScript!".


  • console.log(): Displays a message in the browser’s console, useful for debugging.
  • document.write(): Writes directly to the HTML document. Note: It’s generally not recommended to use this method for dynamic content in modern web development.
  • alert(): Displays a message in a dialog box, which the user must acknowledge before continuing.


In this introduction, we covered:

  • What JavaScript is and its key features.
  • Setting up the development environment, including installing Visual Studio Code and Node.js.
  • Writing and running a basic JavaScript program.

Next Steps

In the next part, we will dive into JavaScript Basics, covering:

  • Variables and Data Types
  • Operators
  • Control Structures (if-else, switch, loops)
  • Functions
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