Request.context

The deprecated 弃用context所述的只读属性请求接口包含请求的上下文（例如，audio，image，iframe）。这定义了要获取的资源类型。它已由Request.destination”，“ destination属性取代。 This defines what sort of resource is being fetched. This has been replaced by the destination (en-US) property.

The context of a request is only relevant in the 请求的上下文仅与ServiceWorker API相关；服务人员可以根据URL是用于图像还是可嵌入对象（例如<视频>，iframe等）进行决策。; 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.

var myContext = request.context;

A RequestContext value.一个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:在以下代码段中，我们使用Request.Request（）}构造函数创建一个新请求（用于与脚本位于同一目录中的图像文件），然后将请求上下文保存在变量中：

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

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