JavaScript

Domains: HTML

JavaScript makes HTML pages more dynamic and interactive.

The HTML <script> Tag

The <script> tag is used to define a client-side script (JavaScript).

The <script> element either contains scripting statements, or it points to an external script file through the src attribute.

Common uses for JavaScript are image manipulation, form validation, and dynamic changes of content.

To select an HTML element, JavaScript very often uses the document.getElementById() method.

This JavaScript example writes "Hello JavaScript!" into an HTML element with id="demo":

<script>
document.getElementById("demo").innerHTML = "Hello JavaScript!";
</script>

Tip: You can learn much more about JavaScript in our JavaScript Tutorial .

A Taste of JavaScript

Here are some examples of what JavaScript can do:

JavaScript can change HTML content

document.getElementById("demo").innerHTML = "Hello JavaScript!";

JavaScript can change HTML styles

document.getElementById("demo").style.fontSize = "25px";
document.getElementById("demo").style.color = "red";
document.getElementById("demo").style.backgroundColor = "yellow";

JavaScript can change HTML attributes

document.getElementById("image").src = "picture.gif";

The HTML <noscript> Tag

The <noscript> tag is used to provide an alternate content for users that have disabled scripts in their browser or have a browser that doesn't support client-side scripts:

<script>
document.getElementById("demo").innerHTML = "Hello JavaScript!";
</script>

<noscript>Sorry, your browser does not support JavaScript!</noscript>

HTML Script Tags

Tag Description
<script> Defines a client-side script
<noscript> Defines an alternate content for users that do not support client-side scripts

Similar pages

Page structure
Terms

HTML

HTML Documents

HTML Tags

The HTML <noscript> Tag

Web Browsers

HTML Element

HTML Attributes

The src Attribute

<picture>

The HTML <script> Tag

The id Attribute