Hello, World!

JavaScript is an interpreted language. That means: no compilation. You just write code and attach it to HTML.

The simplest way is to put JavaScript directives into SCRIPT tag somewhere inside the page.

Here is a SCRIPT tag containing single JavaScript statement. Please click the ‘Show’ button to see the example.



    alert('Hello, World!')



Note that contents of the SCRIPT block is not shown, instead, it is executed.

This example makes use of following elements:

<script> ... </script>
<script> tag tells browser that there is executable content inside. In older HTML standard, namely HTML4, a special attribute type was required. Although more up-to-date HTML5 makes it optional.


  1. Starts showing the page, shows Header
  2. Switches to JavaScript mode inside this tag and executes the contents of <script>
  3. Returns back to HTML-mode and continues with the page, outputs Footer.
Outputs a message window on the screen and awaits until visitor presses OK

Not only reading, but actually testing and doing something on your own is very important. Below you can see a “check yourself” block. It contains a task and the solution.

Fulfil the task to ensure you got eveything right.

Create a page which outputs a “I am JavaScript!”. Save the document and open in the browser. Make sure everything works.

Or, in other words, create the page which works like: tutorial/browser/script/alert/index.html.

Open solution

Open source code of the given example to see the solution or just here: tutorial/browser/script/alert/index.html.

On next pages we’ll go deeper into the examples and basic script building blocks.