Request.context - Web APIs 编辑

Deprecated

This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

The deprecated context read-only property of the Request interface contains the context of the Request (e.g., audio, image, iframe). This defines what sort of resource is being fetched. This has been replaced by the destination property.

The context of a request is only relevant in the ServiceWorker API; a service worker can make decisions based on whether the URL is for an image, or an embeddable object such as a <video>, iframe, etc.

Note: You can find a full list of the different available contexts including associated context frame types, CSP directives, and platform feature examples in the Fetch spec request context section.

Syntax

var myContext = request.context;

Value

A RequestContext value.

Example

In the following snippet, we create a new request using the Request.Request() constructor (for an image file in the same directory as the script), then save the request context in a variable:

var myRequest = new Request('flowers.jpg');
var myContext = myRequest.context; // returns the empty string by default

Browser compatibility

BCD tables only load in the browser

See also

• ServiceWorker API
• HTTP access control (CORS)
• HTTP