HTML <script> Tag

The HTML <script> tag is used for declaring a script within your HTML document.

Many web pages use scripts (usually JavaScript) to provide extra functionality that cannot be accomplished with HTML alone. Any time a script is embedded into an HTML document, it must be enclosed within <script> tags.

Syntax

The <script> tag is written as <script></script> with the script inserted between the start and end tags.

Like this:

Examples

Basic tag usage

Using the <noscript> Tag

You can use the <noscript> tag to provide content for user agents/browsers that don't support scripting.

Any content enclosed between the <noscript> tags is only displayed on browsers that don't support scripting.

Attributes

Attributes can be added to an HTML element to provide more information about how the element should appear or behave.

The <script> element accepts the following attributes.

AttributeDescription
srcSpecifies a URI/URL of an external script.
asyncSpecifies whether a script will executed asynchronously, as soon as it is available.

This is a boolean attribute. If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace (i.e. either async or async="async").

Possible values:

  • [Empty string]
  • async
deferSpecifies whether the script is executed after the page has finished parsing, or immediately. If the async attribute is not present but the defer attribute is present, then the script is executed when the page has finished parsing. If neither attribute is present, then the script is fetched and executed immediately, before the user agent continues parsing the page.

This is a boolean attribute. If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace (i.e. either defer or defer="defer").

Possible values:

  • [Empty string]
  • defer
typeSpecifies the scripting language as a content-type (MIME type).
charsetDefines the character encoding that the script uses.
crossoriginThis attribute is a CORS settings attribute. CORS stands for Cross-Origin Resource Sharing. The purpose of the crossorigin attribute is to allow you to configure the CORS requests for the element's fetched data. The values for the crossorigin attribute are enumerated.

Possible values:

ValueDescription
anonymousCross-origin CORS requests for the element will not have the credentials flag set. In other words, there will be no exchange of user credentials via cookies, client-side SSL certificates or HTTP authentication.
use-credentialsCross-origin CORS requests for the element will have the credentials flag set.

If this attribute is not specified, CORS is not used at all.

An invalid keyword and an empty string will be handled as the anonymous value.

Global Attributes

The following attributes are standard across all HTML elements. Therefore, you can use these attributes with the <script> tag , as well as with all other HTML tags.

For a full explanation of these attributes, see HTML 5 global attributes.

Event Handlers

Event handler content attributes enable you to invoke a script from within your HTML. The script is invoked when a certain "event" occurs. Each event handler content attribute deals with a different event.

Most event handler content attributes can be used on all HTML elements, but some event handlers have specific rules around when they can be used and which elements they are applicable to.

For more detail, see HTML event handler content attributes.