Tag <script> HTML Reference


Display "Hello world" with JavaScript:

<script type="text/javascript">
  alert('Hello World!')

Browser Support

Internet Explorer Firefox Opera Google Chrome Safari

1. Definition and Usage

The <script> tag is used to define a client-side script, such as a JavaScript.

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

The required type attribute specifies the MIME type of the script.

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

2. Tips and Notes

Note: If the "src" attribute is present, the <script> element must be empty.

Tip: Also look at the <noscript> element for users that have disabled scripts in their browser, or have a browser that doesnít support client-side scripting.

3. Differences Between HTML and XHTML

HTML 4 and XHTML deal different with the content inside scripts:

  • In HTML 4, the content type is declared as CDATA, which means that entities will not be parsed.
  • In XHTML, the content type is declared as (#PCDATA), which means that entities will be parsed

This means that in XHTML, all special characters should be encoded or all content should be wrapped inside a CDATA section.

To ensure that a script parses correctly in an XHTML document, use the following syntax:

<script type="text/javascript">
  alert('Hello World!')

4. Required Attributes

DTD indicates in which HTML 4.01/XHTML 1.0 DTD the attribute is allowed. S=Strict, T=Transitional, and F=Frameset.

typeMIME-typeSpecifies the MIME type of the scriptSTF

5. Optional Attributes

charsetcharsetSpecifies the character encoding used in an external script fileSTF
deferdeferSpecifies that the script is executed when the page has finished parsing (only for external scripts)STF
srcURLSpecifies the URL of an external script fileSTF
xml:spacepreserveSpecifies whether whitespace in code should be preserved 

6. Standard Attributes

The <script> tag does not support any standard attributes.

7. Event Attributes

The <script> tag does not support any event attributes.

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