JavaScript Introduction

Getting Started with JavaScript

1. What is JavaScript?

JavaScript is a programming language used to create interactive and dynamic web pages. While HTML provides structure and CSS provides styling, JavaScript adds behavior to websites.

Example:

Click a button and show a message
Validate form input
Update content without refreshing the page

2. Where JavaScript is Used

Web development
Mobile applications
Server-side development (Node.js)
Games
Desktop applications

3. Adding JavaScript to HTML

Inline JavaScript


<button onclick="alert('Hello!')">Click Me</button>

Internal JavaScript


<script>
console.log("Hello JavaScript");
</script>

External JavaScript


<script src="script.js"></script>

script.js


console.log("Welcome to JavaScript Learning");

4. Real Life Example:

index.html


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>JavaScript Using Functions</title>
</head>
<body>
    <!-- inline js -->
    <button onclick="alert('Welcome to JavaScript')">Click here</button>
    <button onclick="callInternal()">Call Internal</button>
    <button onclick="callExternal()">Call External</button>


    <!-- Internal Js -->
    <script>
        function callInternal(){
            alert('Alert from Internal JavaScript');
            console.log("Console output from Internal JS");
        }
    </script>

    <!-- External Js -->
    <script src="myscript.js"></script>
</body>
</html>

Run Code

myscript.js


function callExternal(){
    alert('Alert from External JavaScript');
    console.log("Console output from External JS");
}

Run Code

5. What Students Learned

What JavaScript is
How to add JavaScript to HTML
Basic interaction with HTML elements
Writing a simple function

Next Chapter

Chapter 2: Variables, Data Types, and Operators

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