fetch-polyfill
v0.8.2
Published
**This fork supports IE8 with es5-shim, es5-sham and es6-promise**
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window.fetch polyfill
This fork supports IE8 with es5-shim, es5-sham and es6-promise
This module is out of maintanance, use fetch-ie8 instead.
The global fetch
function is an easier way to make web requests and handle
responses than using an XMLHttpRequest. This polyfill is written as closely as
possible to the standard Fetch specification at https://fetch.spec.whatwg.org.
Installation
Available on Bower as fetch-polyfill.
$ bower install fetch-polyfill
You'll also need a Promise polyfill for older browsers.
$ bower install es6-promise
This can also be installed with npm
.
$ npm install fetch-polyfill --save
(For a node.js implementation, try node-fetch)
Usage
The fetch
function supports any HTTP method. We'll focus on GET and POST
example requests.
HTML
fetch('/users.html')
.then(function(response) {
return response.text()
}).then(function(body) {
document.body.innerHTML = body
})
JSON
fetch('/users.json')
.then(function(response) {
return response.json()
}).then(function(json) {
console.log('parsed json', json)
}).catch(function(ex) {
console.log('parsing failed', ex)
})
Response metadata
fetch('/users.json').then(function(response) {
console.log(response.headers.get('Content-Type'))
console.log(response.headers.get('Date'))
console.log(response.status)
console.log(response.statusText)
})
Post form
var form = document.querySelector('form')
fetch('/query', {
method: 'post',
body: new FormData(form)
})
Post JSON
fetch('/users', {
method: 'post',
headers: {
'Accept': 'application/json',
'Content-Type': 'application/json'
},
body: JSON.stringify({
name: 'Hubot',
login: 'hubot',
})
})
File upload
var input = document.querySelector('input[type="file"]')
var form = new FormData()
form.append('file', input.files[0])
form.append('user', 'hubot')
fetch('/avatars', {
method: 'post',
body: form
})
Success and error handlers
This causes fetch
to behave like jQuery's $.ajax
by rejecting the Promise
on HTTP failure status codes like 404, 500, etc. The response Promise
is
resolved only on successful, 200 level, status codes.
function status(response) {
if (response.status >= 200 && response.status < 300) {
return response
}
throw new Error(response.statusText)
}
function json(response) {
return response.json()
}
fetch('/users')
.then(status)
.then(json)
.then(function(json) {
console.log('request succeeded with json response', json)
}).catch(function(error) {
console.log('request failed', error)
})
Response URL caveat
The Response
object has a URL attribute for the final responded resource.
Usually this is the same as the Request
url, but in the case of a redirect,
its all transparent. Newer versions of XHR include a responseURL
attribute
that returns this value. But not every browser supports this. The compromise
requires setting a special server side header to tell the browser what URL it
just requested (yeah, I know browsers).
response.headers['X-Request-URL'] = request.url
If you want response.url
to be reliable, you'll want to set this header. The
day that you ditch this polyfill and use native fetch only, you can remove the
header hack.
Browser Support
| | | | --- | --- | --- | --- | --- | Latest ✔ | Latest ✔ | 8+ ✔ | Latest ✔ | 6.1+ ✔ |