• 07 Oct, 2022

JavaScript

JavaScript

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JavaScript is a scripting language that is mostly used in web development. JavaScript runs in the front-end, so it can update HTML elements, connect to a server (e.g Database server, File Server etc.), change page style (CSS) and more.

You can learn JavaScript here: https://www.learn-js.org/

JavaScript in HTML file

HTML has the <script> tag, which allows scripts in a web page.

Example:

<!DOCTYPE html>
<html>
<head>
<title>JavaScript</title>
</head>
<body>
    <p>Hello, JavaScript!</p>
</body>
<script>
console.log("Hello World!");
</script>
</html>

"Hello World!" will show in your browser's console.

External JavaScript

You can import a JavaScript (.js) file. This is useful for organizing your website.

JS File (example.js):

console.log("Hello World!");

HTML File:

<!DOCTYPE html>
<html>
<head>
<title>External JavaScript</title>
</head>
<body>
<p>External JavaScript!</p>
</body>
<script src="example.js"></script>
</html>

The src attribute, imports the specified JavaScript file.

Also the src attribute, can import scripts from a CDN (Content Delivery Network). That is mostly used for including JavaScript libraries.

<!DOCTYPE html>
<html>
<head>
<title>External CDN JavaScript</title>
</head>
<body>
<p>External CDN JavaScript!</p>
</body>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
</html>

The type attribute

The <script> tag has the type attribute, which specifies the scripting language that is going to be used in the <script> tag. Now it's almost obsolete. JavaScript is the default.

They would use this in the HTML4 days:

<html>
<head>
<title>Other scripting languages</title>
</head>
<body>
<p>Other scripting languages</p>
</body>
<script type="text/javascript">
console.log("Hello World");
</script>
</html>

Do it Yourself

  1. Add JavaScript code after </body>. The code must be alert("Hello World!"); (This will popup "Hello World!")