弃用
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
兼容性表格
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
只读特性在
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 This has been replaced by the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
特性。
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
，等。
注意 : 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 章节。
var myContext = request.context;
A
RequestContext
值。
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
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
context
弃用
非标
|
Chrome 42 — 46 | Edge ? |
Firefox
39 — 42
|
IE No | Opera 28 — 29 | Safari No | WebView Android 42 — 46 | Chrome Android 42 — 46 | Firefox Android No | Opera Android No | Safari iOS No | Samsung Internet Android 4.0 — 5.0 |
不支持
兼容性未知
实验。期望将来行为有所改变。
非标。预期跨浏览器支持较差。
弃用。不要用于新网站。
见实现注意事项。