Max Script Download

[Kathy Douds]

The HTML element is used to embed executable code or data; this is typically used to embed or refer to JavaScript code. The element can also be used with other languages, such as WebGL's GLSL shader programming language and JSON.

This attribute allows the elimination of parser-blocking JavaScript where the browser would have to load and evaluate scripts before continuing to parse. defer has a similar effect in this case.

Specifies that you want the browser to send an Attribution-Reporting-Eligible header along with the script resource request. On the server-side this is used to trigger sending an Attribution-Reporting-Register-Source or Attribution-Reporting-Register-Trigger header in the response, to register a JavaScript-based attribution source or attribution trigger, respectively. Which response header should be sent back depends on the value of the Attribution-Reporting-Eligible header that triggered the registration.

Note: Alternatively, JavaScript-based attribution sources or triggers can be registered by sending a fetch() request containing the attributionReporting option (either set directly on the fetch() call or on a Request object passed into the fetch() call), or by sending an XMLHttpRequest with setAttributionReporting() invoked on the request object.

Note: Specifying multiple URLs means that multiple attribution sources can be registered on the same feature. You might for example have different campaigns that you are trying to measure the success of, which involve generating different reports on different data.

This attribute explicitly indicates that certain operations should be blocked on the fetching of the script. The operations that are to be blocked must be a space-separated list of blocking tokens listed below.

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 attribute allows the elimination of parser-blocking JavaScript where the browser would have to load and evaluate scripts before continuing to parse. async has a similar effect in this case.

This attribute contains inline metadata that a user agent can use to verify that a fetched resource has been delivered without unexpected manipulation. The attribute must not specified when the src attribute is not specified. See Subresource Integrity.

A cryptographic nonce (number used once) to allow 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.

Note: An empty string value ("") is both the default value, and a fallback value if referrerpolicy is not supported. If referrerpolicy is not explicitly specified on the element, it will adopt a higher-level referrer policy, i.e. one set on the whole document or domain. If a higher-level policy is not available, the empty string is treated as being equivalent to strict-origin-when-cross-origin.

Indicates that the script is a "classic script", containing JavaScript code. Authors are encouraged to omit the attribute if the script refers to JavaScript code rather than specify a MIME type. JavaScript MIME types are listed in the IANA media types specification.

This value indicates that the body of the element contains an import map. The import map is a JSON object that developers can use to control how the browser resolves module specifiers when importing JavaScript modules.

This value causes the code to be treated as a JavaScript module. The processing of the script contents is deferred. The charset and defer attributes have no effect. For information on using module, see our JavaScript modules guide. Unlike classic scripts, module scripts require the use of the CORS protocol for cross-origin fetching.

This value indicates that the body of the element contains speculation rules. Speculation rules take the form of a JSON object that determine what resources should be prefetched or prerendered by the browser. This is part of the Speculation Rules API.

The embedded content is treated as a data block, and 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. All of the other attributes will be ignored, including the src attribute.

If present, its value must be an ASCII case-insensitive match for "utf-8". It's unnecessary to specify the charset attribute, because documents must use UTF-8, and the script element inherits its character encoding from the document.

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, defer or type="module" attributes, as well as inline scripts without the type="module" attribute, are fetched and executed immediately before the browser continues to parse the page.

Scripts loaded using the async attribute will download the script without blocking the page while the script is being fetched. However, once the download is complete, the script will execute, which blocks the page from rendering. This means that the rest of the content on the web page is prevented from being processed and displayed to the user until the script finishes executing. You get no guarantee that scripts will run in any specific order. It is best to use async when the scripts in the page run independently from each other and depend on no other script on the page.

Scripts loaded with the defer attribute will load in the order they appear on the page. They won't run until the page content has all loaded, which is useful if your scripts depend on the DOM being in place (e.g. they modify one or more elements on the page).

You can't rely on the order the scripts will load in. jquery.js may load before or after script2.js and script3.js and if this is the case, any functions in those scripts depending on jquery will produce an error because jquery will not be defined at the time the script runs.

async should be used when you have a bunch of background scripts to load in, and you just want to get them in place as soon as possible. For example, maybe you have some game data files to load, which will be needed when the game actually begins, but for now you just want to get on with showing the game intro, titles, and lobby, without them being blocked by script loading.

In the second example, we can be sure that jquery.js will load before script2.js and script3.js and that script2.js will load before script3.js. They won't run until the page content has all loaded, which is useful if your scripts depend on the DOM being in place (e.g. they modify one or more elements on the page).

Browsers that support the module value for the type attribute ignore any script with a nomodule attribute. That enables you to use module scripts while providing nomodule-marked fallback scripts for non-supporting browsers.

When importing modules in scripts, if you don't use the type=importmap feature, then each module must be imported using a module specifier that is either an absolute or relative URL. In the example below, the first module specifier ("./shapes/square.js") resolves relative to the base URL of the document, while the second is an absolute URL.

An import map allows you to provide a mapping that, if matched, can replace the text in the module specifier. The import map below defines keys square and circle that can be used as aliases for the module specifiers shown above.

You can include render token inside a blocking attribute; the rendering of the page will be blocked till the script is fetched and executed. In the example below, we block rendering on an async script, so that the script doesn't block parsing but is guaranteed to be evaluated before rendering starts.