Fetchify

Fetchify is a fork of Github's window.fetch polyfill

It is adapted to be used primarily within Node as part of a Browserify bundle. It is also tested and pluggable with various Promise implementations such as Bluebird and Q

window.fetch polyfill

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

Install with npm.

$ npm install fetchify --save

Usage

The fetch function supports any HTTP method. We'll focus on GET and POST example requests.

Node

Example using Bluebird

var Promise = require('bluebird');
 
var fetch = require('fetchify')(Promise).fetch;
 
//Headers, Request and Response are also exported
var Headers = require('fetchify')(Promise).Headers;
var Request = require('fetchify')(Promise).Request;
var Response = require('fetchify')(Promise).Response;
 
fetch('/users.html')
  .then(function(response) {
    return response.text()
  }).then(function(body) {
    document.body.innerHTML = body
  })

You could also use Q

var Promise = require('q').Promise;
 
var fetch = require('fetchify')(Promise).fetch;

In the browser

Fetchify also provides a browser polyfill build (see the dist directory).

If you don't want to globally polyfill a Promise impl, you can also inject it:

<script src="fetch.min.js"></script>
<script>
    fetch.promiseImpl(Q.Promise);
    var result = fetch('data.json')
</script> 

More examples

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 Promise.resolve(response)
  } else {
    return Promise.reject(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)
  })

Browser Support

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