Here is a basic “Hello World!” exercise in JavaScript. Online code editors like JSFiddle and Codepen truly come into their own when learning JavaScript. This simple example uses JavaScript’s alert method to display a “pop-up” type message when the page loads (this is not a good thing to do on your website, by the way, it is considered intrusive).

1. jsFiddle

2. Codepen

See the Pen Hello World! by David Fox (@foxbeefly) on CodePen.

3. HTML Web page

Or copy-paste the below code into an HTML file and fire up your browser!

		<title>Hello World! JavaScript</title>
		<h1>Hello World! JavaScript</h1>
			alert("Hello World!");

JavaScript code can be written in your HTML files between the <script> tags. The <script> tags are in turn nested in the <head> or <body> tags.

4. methods & functions

A function is a reusable block of code that does something and can be called from somewhere. A method is a function that belongs to an object. The alert() function is a method of the Window object. JavaScript has many, many “built-in” objects with methods for you to use, and of course, later you will write your own. [1]

This is a bit advanced for now — for now, just bear these terms in mind.

5. Next steps

Your next step is to use an event to fire your JavaScript code. Head on over to the Javascipt’s onclick() event tutorial.


  1. MozDevNet (no date) Functions – reusable blocks of code – Learn web development: MDNMDN Web Docs. Available at: (Accessed: 8 January 2024).
  2. MozDevNet (no date) Function return values – Learn web development: MDNMDN Web Docs. Available at: (Accessed: 8 January 2024).

By MisterFoxOnline

Mister Fox AKA @MisterFoxOnline is an ICT, IT and CAT Teacher who has just finished training as a Young Engineers instructor. He has a passion for technology and loves to find solutions to problems using the skills he has learned in the course of his IT career.

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