README.md

    window.fetch polyfill

    This project adheres to the [Open Code of Conduct][code-of-conduct]. By participating, you are expected to uphold this code. [code-of-conduct]: http://todogroup.org/opencodeofconduct/#fetch/opensource@github.com

    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.

    $ bower install fetch

    You'll also need a Promise polyfill for older browsers.

    $ bower install es6-promise

    This can also be installed with npm.

    $ npm install whatwg-fetch --save

    For a node.js implementation, try node-fetch.

    For use with webpack, refer to Using WebPack with shims and polyfills.

    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('/users', {
      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 data = new FormData()
    data.append('file', input.files[0])
    data.append('user', 'hubot')
    
    fetch('/avatars', {
      method: 'post',
      body: data
    })

    Caveats

    The fetch specification differs from jQuery.ajax() in mainly two ways that bear keeping in mind:

    • The Promise returned from fetch() won't reject on HTTP error status even if the response is a HTTP 404 or 500. Instead, it will resolve normally, and it will only reject on network failure, or if anything prevented the request from completing.

    • By default, fetch won't send any cookies to the server, resulting in unauthenticated requests if the site relies on maintaining a user session.

    Handling HTTP error statuses

    To have fetch Promise reject on HTTP error statuses, i.e. on any non-2xx status, define a custom response handler:

    function checkStatus(response) {
      if (response.status >= 200 && response.status < 300) {
        return response
      } else {
        var error = new Error(response.statusText)
        error.response = response
        throw error
      }
    }
    
    function parseJSON(response) {
      return response.json()
    }
    
    fetch('/users')
      .then(checkStatus)
      .then(parseJSON)
      .then(function(data) {
        console.log('request succeeded with JSON response', data)
      }).catch(function(error) {
        console.log('request failed', error)
      })

    Sending cookies

    To automatically send cookies for the current domain, the credentials option must be provided:

    fetch('/users', {
      credentials: 'same-origin'
    })

    This option makes fetch behave similar to XMLHttpRequest with regards to cookies. Otherwise, cookies won't get sent, resulting in these requests not preserving the authentication session.

    Use the include value to send cookies in a cross-origin resource sharing (CORS) request.

    fetch('https://example.com:1234/users', {
      credentials: 'include'
    })

    Receiving cookies

    Like with XMLHttpRequest, the Set-Cookie response header returned from the server is a forbidden header name and therefore can't be programatically read with response.headers.get(). Instead, it's the browser's responsibility to handle new cookies being set (if applicable to the current URL). Unless they are HTTP-only, new cookies will be available through document.cookie.

    Obtaining the Response URL

    Due to limitations of XMLHttpRequest, the response.url value might not be reliable after HTTP redirects on older browsers.

    The solution is to configure the server to set the response HTTP header X-Request-URL to the current URL after any redirect that might have happened. It should be safe to set it unconditionally.

    # Ruby on Rails controller example
    response.headers['X-Request-URL'] = request.url

    This server workaround is necessary if you need reliable response.url in Firefox < 32, Chrome < 37, Safari, or IE.

    Browser Support

    Chrome Firefox IE Opera Safari
    Latest Latest 9+ Latest 6.1+

    项目简介

    A window.fetch JavaScript polyfill.

    🚀 Github 镜像仓库 🚀

    源项目地址

    https://github.com/github/fetch

    发行版本 55

    v3.6.19

    全部发行版

    贡献者 81

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    开发语言

    • JavaScript 99.5 %
    • Makefile 0.5 %