提取与AjaxCall [英] Fetch vs. AjaxCall

问题描述

典型的AJAX和Fetch API有什么区别?

What is the difference between typical AJAX and Fetch API?

考虑这种情况:

function ajaxCall(url) {
  return new Promise(function(resolve, reject) {
    var req = new XMLHttpRequest();
    req.open('GET', url);

    req.onload = function() {
      if (req.status == 200) {
        resolve(req.response);
      } else {
        reject(Error(req.statusText));
      }
    };
    req.onerror = function() {
      reject(Error("Network Error"));
    };
    req.send();
  });
}

ajaxCall('www.testSite').then(x => {
  console.log(x)
}) // returns html of site

fetch('www.testSite').then(x => {
  console.log(x)
}) // returns object with information about call

这是fetch调用返回的内容:

Response {type: "cors", url: "www.testSite", status: 200, ok: true, statusText: "OK"…}

为什么它返回不同的东西?

Why does it return different things?

fetch是否可以返回与典型AJAX调用相同的内容?

Is there a way for fetch to return the same thing as a typical AJAX call?

推荐答案

Fetch API内置了适用于不同数据类型的方法.
对于普通的text/html，您可以使用text()方法，该方法也会返回一个promise，并将其与另一个调用链接.

The Fetch API has built in methods for different datatypes.
For just regular text/html you'd use the text() method, which returns a promise as well, and chain it with another then call.

fetch('www.testSite').then( x => { 
    return x.text();
}).then( y => {
    console.log(y);
});

返回的内容的内置内容如下

The built-ins for the returned content is as follows

• clone()-创建Response对象的克隆.
• error()-返回一个 与网络错误相关联的新Response对象.
• redirect()-使用其他URL创建新的响应.
• arrayBuffer()-返回使用ArrayBuffer解析的promise.
• blob()-返回以Blob解析的promise.
• formData()-返回使用FormData对象解析的Promise.
• json()-返回使用JSON对象解析的承诺.
• text()-返回以USVString(文本)解析的承诺.

• clone() - Creates a clone of a Response object.
• error() - Returns a new Response object associated with a network error.
• redirect() - Creates a new response with a different URL.
• arrayBuffer() - Returns a promise that resolves with an ArrayBuffer.
• blob() - Returns a promise that resolves with a Blob.
• formData() - Returns a promise that resolves with a FormData object.
• json() - Returns a promise that resolves with a JSON object.
• text() - Returns a promise that resolves with a USVString (text).

它还允许您将内容发送到服务器，或添加自己的标头等.

It also allows you to send things to the server, or add your own headers etc.

fetch('www.testSite', {
    method  : 'post',
    headers : new Headers({
        'Content-Type': 'application/x-www-form-urlencoded'
    }),
    body    : new FormData(document.getElementById('myform'))
}).then( response => {
    return response.json(); // server returned valid JSON
}).then( parsed_result => {
    console.log(parsed_result);
});

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