Fetch API
This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
The Fetch API provides an interface for fetching resources (including across the network). It will seem familiar to anyone who has used XMLHttpRequest
, but the new API provides a more powerful and flexible feature set.
Concepts and usage
Fetch provides a generic definition of Request
and Response
objects (and other things involved with network requests). This will allow them to be used wherever they are needed in the future, whether it’s for service workers, Cache API and other similar things that handle or modify requests and responses, or any kind of use case that might require you to generate your own responses programmatically.
It also provides a definition for related concepts such as CORS and the HTTP origin header semantics, supplanting their separate definitions elsewhere.
For making a request and fetching a resource, use the GlobalFetch.fetch
method. It is implemented in multiple interfaces, specifically Window
and WorkerGlobalScope
. This makes it available in pretty much any context you might want to fetch resources in.
The fetch()
method takes one mandatory argument, the path to the resource you want to fetch. It returns a promise that resolves to the Response
to that request, whether it is successful or not. You can also optionally pass in an init
options object as the second argument (see Request
.)
Once a Response
is retrieved, there are a number of methods available to define what the body content is and how it should be handled (see Body
.)
You can create a request and response directly using the Request()
and Response()
constructors, but you are unlikely to do this directly. Instead, these are more likely to be created as results of other API actions (for example, FetchEvent.respondWith
from service workers.)
Note: Find out more about using the Fetch API features in Using Fetch, and study concepts in Fetch basic concepts.
Fetch Interfaces
GlobalFetch
- Contains the
fetch()
method used to fetch a resource. Headers
- Represents response/request headers, allowing you to query them and take different actions depending on the results.
Request
- Represents a resource request.
Response
- Represents the response to a request.
Fetch mixin
Body
- Provides methods relating to the body of the response/request, allowing you to declare what its content type is and how it should be handled.
Specifications
Specification | Status | Comment |
---|---|---|
Fetch | Living Standard | Initial definition |
Browser compatibility
Feature | Chrome | Edge | Firefox (Gecko) | IE | Opera | Safari (WebKit) |
---|---|---|---|---|---|---|
Basic support | 42.0 |
14 |
39 (39) 34 behind pref |
No support |
29 |
No support WebKit bug 151937 |
Streaming response body | 43.0 |
14 |
? |
? |
? |
? |
Feature | Android | Android Webview | Firefox Mobile (Gecko) | Firefox OS (Gecko) | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|---|
Basic support | No support | 42.0 | No support | No support | No support | No support | No support | 42.0 |
Streaming response body | No support | 43.0 |
? |
? |
? |
? |
? |
43.0 |
See also
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/api/fetch_api