jQuery访问XMLHttpRequest吗? [英] JQuery Access XMLHttpRequest?

问题描述

JQuery ajax 文档表示，您可以通过以下方式访问XMLHttpRequest:

The JQuery ajax documentation said that you can get access to the XMLHttpRequest by the following:

var jqxhr = $.ajax({
      xhr: function() {
          var xhrNativeObject = new window.XMLHttpRequest();
          xhrNativeObject.upload.addEventListener("progress", function(event) { 
               // progress bar 
          }, false);
          return xhrNativeObject;
      },
      url: url,
  type: "POST",
  data: formdata,
  processData: false,
  contentType: false
    }).then(function(response) { 
         ...         
    });
   jqxhr.abort();  // this is not working!!!

当我在控制台中打印jqxhr时，这对我不起作用:

This is not working for me when I print jqxhr in my console I get:

Object {url: "http://someurl", isLocal: false, global: true, type: "POST", contentType: false…} 

执行以下操作时，我只会获得XMLHttpRequest:

I only get the XMLHttpRequest when I do the following:

var myXHR;
$.ajax({
   xhr: function() { 
      myXHR = new window.XMLHttpRequest(); 
   }
 ... });

当我在控制台上打印myXHR时，我得到:

When I print myXHR on my console I get:

XMLHttpRequest {open: function, setRequestHeader: function, send: function, abort: function, getAllResponseHeaders: function…}

这是正确的.

JQuery文档说我可以对jqxhr对象执行abort().何时做:

The JQuery docu said that I can do abort() on the jqxhr object. When do do:

jqxhr.abort();

我收到以下控制台错误:

I get the following console error:

Uncaught TypeError: Object #<Object> has no method 'abort'

我这样做

myXHR.abort();

一切正常.

为什么abort()在jqxhr对象上不起作用?

使用JQuery 1.8.3

Using JQuery 1.8.3

我创建了一个示例: http://jsfiddle.net/9HmQd/ 事实证明，当我添加then()块时，中止是不确定的.

I created an example: http://jsfiddle.net/9HmQd/ It turns out that abort is undefined when I add the then() block.

推荐答案

使用.ajax()时，它返回一种特殊的承诺，即 promise 对象，该对象将不具有与jqXhr关联的方法-在您的情况下，此诺言是由于链接而分配给xhr变量的值.

When you use .ajax(), it returns a special kind of promise which is the jqXHR object, but when you call then on the jqxhr, it returns a promise object which will not have methods associated with jqXhr - in your case this promise is the value assigned to the xhr variable because of chaining.

解决方案

var xhr = $.ajax({
    url: '/echo/json'
});
xhr.then(function (response) {})

console.log(xhr.abort);

演示:小提琴

这篇关于jQuery访问XMLHttpRequest吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！