The <script> is used to embed or reference executable code; this is typically used to embed or refer to JavaScript code. The <script> element can also be used with other languages, such as WebGL's GLSL shader programming language.

Content categories Metadata content, Flow content, Phrasing content.
Permitted content Dynamic script such as text/javascript.
Tag omission None, both the starting and ending tag are mandatory.
Permitted parents Any element that accepts metadata content, or any element that accepts phrasing content.
Permitted ARIA roles None
DOM interface HTMLScriptElement


This element includes the global attributes.

async HTML5
This is a Boolean attribute indicating that the browser should, if possible, execute the script asynchronously.

This attribute must not be used if the src attribute is absent (i.e. for inline scripts). If it is included in this case it will have no effect.

Dynamically inserted scripts execute asynchronously by default, so to turn on synchronous execution (i.e. scripts execute in the order they were inserted) set async=false.

See Browser compatibility for notes on browser support. See also Async scripts for asm.js.
Normal script elements pass minimal information to the window.onerror for scripts which do not pass the standard CORS checks. To allow error logging for sites which use a separate domain for static media, use this attribute. See CORS settings attributes for a more descriptive explanation of its valid arguments.
This Boolean attribute is set to indicate to a browser that the script is meant to be executed after the document has been parsed, but before firing DOMContentLoaded.

This attribute must not be used if the src attribute is absent (i.e. for inline scripts), in this case it would have no effect.

To achieve a similar effect for dynamically inserted scripts use async=false instead. Scripts with the defer attribute will execute in the order in which they appear in the document.
This attribute contains inline metadata that a user agent can use to verify that a fetched resource has been delivered free of unexpected manipulation. See Subresource Integrity.
This Boolean attribute is set to indicate that the script should not be executed in browsers that support ES6 modules — in effect, this can be used to serve fallback scripts to older browsers that do not support modular JavaScript code.

This is an experimental API and should not be used in production code.

A cryptographic nonce (number used once) to whitelist inline scripts in a script-src Content-Security-Policy. The server must generate a unique nonce value each time it transmits a policy. It is critical to provide a nonce that cannot be guessed as bypassing a resource's policy is otherwise trivial.
This attribute specifies the URI of an external script; this can be used as an alternative to embedding a script directly within a document.

If a script element has a src attribute specified, it should not have a script embedded inside its tags.

Like the textContent attribute, this attribute sets the text content of the element. Unlike the textContent attribute, however, this attribute is evaluated as executable code after the node is inserted into the DOM.

This attribute indicates the type of script represented. The value of this attribute will be in one of the following categories:

  • Omitted or a JavaScript MIME type: For HTML5-compliant browsers this indicates the script is JavaScript. HTML5 specification urges authors to omit the attribute rather than provide a redundant MIME type. In earlier browsers, this identified the scripting language of the embedded or imported (via the src attribute) code. JavaScript MIME types are listed in the specification.
  • module HTML5 For HTML5-compliant browsers the code is treated as a JavaScript module. The processing of the script contents is not affected by the charset and defer attributes. For information on using module, see ES6 in Depth: Modules.
  • Any other value: The embedded content is treated as a data block which won't be processed by the browser. Developers must use a valid MIME type that is not a JavaScript MIME type to denote data blocks. The src attribute will be ignored.

Note: in Firefox you can use advanced features such as 'let' statements and other features in later JS versions, by using type=application/javascript;version=1.8 .

Beware, however, that as this is a non-standard feature, this will most likely break support for other browsers, in particular Chromium-based browsers. For how to include 'exotic programming languages', read about Rosetta.

Deprecated attributes

Like the type attribute, this attribute identifies the scripting language in use. Unlike the type attribute, however, this attribute’s possible values were never standardized. The type attribute should be used instead.


Scripts without async or defer attributes, as well as inline scripts, are fetched and executed immediately, before the browser continues to parse the page.

The script should be served with the text/javascript MIME type, but browsers are lenient and only block them if the script is served with an image type (image/*); a video type (video/*); an audio (audio/*) type; or text/csv. If the script is blocked, an error is sent to the element, if not a load event is sent.


<!-- HTML4 and (x)HTML -->
<script type="text/javascript" src="javascript.js"></script>

<!-- HTML5 -->
<script src="javascript.js"></script>


Browser compatibility

The information shown below has been pulled from MDN's Github (https://github.com/mdn/browser-compat-data)

Feature Chrome Edge Firefox Internet Explorer Opera Safari
Basic support 1 Yes 11 Yes Yes Yes
async 1 Yes 1 Yes Yes Yes
crossorigin 30 Yes 13 No 12 Yes2
defer Yes Yes 3.53 104 No Yes
integrity 45 No 43 No ? No5
language 1 Yes 1 Yes Yes Yes
nomodule Yes No Yes6 No No No
src 1 Yes 1 Yes Yes Yes
text 1 Yes 1 Yes Yes Yes
type 1 Yes 1 Yes Yes Yes
type.module 61 16 Yes6 No 48 10.1
Feature Android webview Chrome for Android Edge mobile Firefox for Android Opera Android iOS Safari Samsung Internet
Basic support Yes Yes Yes 4 Yes Yes ?
async Yes Yes Yes 4 Yes Yes ?
crossorigin Yes Yes ? 14 ? ? ?
defer Yes Yes Yes 4 ? Yes ?
integrity 45 45 No 43 ? No ?
language Yes Yes Yes 4 Yes Yes ?
nomodule Yes Yes No Yes6 ? No ?
src Yes Yes Yes 4 Yes Yes ?
text Yes Yes Yes 4 Yes Yes ?
type Yes Yes Yes 4 Yes Yes ?
type.module 61 61 16 Yes6 48 10.3 ?

1. Starting in Firefox 4, inserting <script> elements that have been created by calling document.createElement("script") no longer enforces execution in insertion order. This change lets Firefox properly abide by the specification. To make script-inserted external scripts execute in their insertion order, set .async=false on them.

2. The crossorigin attribute was implemented in WebKit in WebKit bug 81438.

3. Since Firefox 3.6, the defer attribute is ignored on scripts that don't have the src attribute. However, in Firefox 3.5 even inline scripts are deferred if the defer attribute is set.

4. In versions prior to Internet Explorer 10, it implemented >script< by a proprietary specification. Since version 10 it conforms to the W3C specification.

5. WebKit bug 148363 tracks WebKit implementation of Subresource Integrity (which includes the integrity attribute).

6. This feature is behind the dom.moduleScripts.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.

Compatibility notes

In older browsers that don't support the async attribute, parser-inserted scripts block the parser; script-inserted scripts execute asynchronously in IE and WebKit, but synchronously in Opera and pre-4 Firefox. In Firefox 4, the async> DOM property defaults to true for script-created scripts, so the default behaviour matches the behaviour of IE and WebKit.

To request script-inserted external scripts be executed in the insertion order in browsers where the document.createElement("script").async evaluates to true (such as Firefox 4), set .async=false on the scripts you want to maintain order.

Never call document.write() from an async script. In Firefox 3.6, calling document.write() has an unpredictable effect. In Firefox 4, calling document.write() from an async script has no effect (other than printing a warning to the error console).

See also

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