JavaScript can be integrated into an HTML document in several ways.
Inline JavaScript
Inline JavaScript is written directly within your HTML elements. It’s used to handle simple, quick JavaScript functionality.
<button onclick="alert('Hello, World!');">Click me</button>
Internal JavaScript
Internal JavaScript is written inside the <script> tags in the HTML document. This is useful when the JavaScript code is not too large.
<script>
function greet() {
alert('Hello, World!');
}
</script>
<button onclick="greet();">Click me</button>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Your Web Page Title</title>
<!-- Inline JavaScript -->
<script>
// Your JavaScript code goes here
function greet() {
alert('Hello, World!');
}
</script>
</head>
<body>
<!-- Your content goes here -->
<!-- Call the JavaScript function -->
<button onclick="greet()">Click me</button>
</body>
</html>
External JavaScript
External JavaScript is written in a separate file with a .js extension. This file is then linked to the HTML document using the <script> tag with the src attribute. This is useful when you have a large amount of JavaScript code or when you want to use the same JavaScript code in multiple HTML files.
<script src="script.js"></script>
In the script.js file:
function greet() {
alert('Hello, World!');
}
In the HTML file:
<button onclick="greet();">Click me</button>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Your Web Page Title</title>
<!-- External JavaScript -->
<script src="script.js"></script>
</head>
<body>
<!-- Your content goes here -->
<!-- Call the JavaScript function -->
<button onclick="greet()">Click me</button>
</body>
</html>