From http://www.w3schools.com (Copyright Refsnes Data)

HTML <script> tag

Example

Insert a JavaScript in an HTML page:

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.

Browser Support

The <script> tag is supported in all major browsers.

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:

Tips and Notes

Tip: Also look at the noscript element for users that have disabled scripts in their browser or have a browser that doesn’t support client-side scripting.

Required Attributes

DTD indicates in which DTD the attribute is allowed. S=Strict, T=Transitional, and F=Frameset.

Attribute	Value	Description	DTD
type	MIME-type	Specifies the MIME type of a script	STF

Optional Attributes

Attribute	Value	Description	DTD
charset	charset	Specifies the character encoding used in an external script file	STF
defer	defer	Specifies that the execution of a script should be deferred (delayed) until after the page has been loaded	STF
src	URL	Specifies the URL of an external script file	STF
xml:space	preserve	Specifies whether whitespace in code should be preserved

Standard Attributes

NONE

Event Attributes

NONE