jQuery.ajax 处理继续响应:“成功:"与“.完成"?

success 一直是 jQuery 中成功回调的传统名称，定义为 ajax 调用中的一个选项.然而，由于 $.Deferreds 和更复杂的回调的实现，done 是实现成功回调的首选方式，因为它可以在任何 deferred代码>.

success has been the traditional name of the success callback in jQuery, defined as an option in the ajax call. However, since the implementation of $.Deferreds and more sophisticated callbacks, done is the preferred way to implement success callbacks, as it can be called on any deferred.

例如，成功:

$.ajax({
  url: '/',
  success: function(data) {}
});

例如完成:

$.ajax({url: '/'}).done(function(data) {});

done 的好处是 $.ajax 的返回值现在是一个延迟承诺，可以绑定到应用程序中的任何其他地方.因此，假设您想从几个不同的地方进行这个 ajax 调用.而不是将您的成功函数作为选项传递给进行此 ajax 调用的函数，您可以让函数返回 $.ajax 本身并使用 done 绑定您的回调、fail、then 或其他.请注意，always 是一个回调，无论请求成功还是失败都会运行.done 只会在成功时触发.

The nice thing about done is that the return value of $.ajax is now a deferred promise that can be bound to anywhere else in your application. So let's say you want to make this ajax call from a few different places. Rather than passing in your success function as an option to the function that makes this ajax call, you can just have the function return $.ajax itself and bind your callbacks with done, fail, then, or whatever. Note that always is a callback that will run whether the request succeeds or fails. done will only be triggered on success.

例如:

function xhr_get(url) {

  return $.ajax({
    url: url,
    type: 'get',
    dataType: 'json',
    beforeSend: showLoadingImgFn
  })
  .always(function() {
    // remove loading image maybe
  })
  .fail(function() {
    // handle request failures
  });

}

xhr_get('/index').done(function(data) {
  // do stuff with index data
});

xhr_get('/id').done(function(data) {
  // do stuff with id data
});

这在可维护性方面的一个重要好处是您已将 ajax 机制包装在特定于应用程序的函数中.如果您决定将来需要 $.ajax 调用以不同方式操作，或者您使用不同的 ajax 方法，或者您不再使用 jQuery，则只需更改 xhr_get 定义(确保返回一个承诺或至少一个 done 方法，在上面的例子中).整个应用程序中的所有其他引用都可以保持不变.

An important benefit of this in terms of maintainability is that you've wrapped your ajax mechanism in an application-specific function. If you decide you need your $.ajax call to operate differently in the future, or you use a different ajax method, or you move away from jQuery, you only have to change the xhr_get definition (being sure to return a promise or at least a done method, in the case of the example above). All the other references throughout the app can remain the same.

你可以用 $.Deferred 做更多(更酷)的事情，其中​​之一是使用 pipe 来触发失败报告的错误服务器，即使 $.ajax 请求本身成功.例如:

There are many more (much cooler) things you can do with $.Deferred, one of which is to use pipe to trigger a failure on an error reported by the server, even when the $.ajax request itself succeeds. For example:

function xhr_get(url) {

  return $.ajax({
    url: url,
    type: 'get',
    dataType: 'json'
  })
  .pipe(function(data) {
    return data.responseCode != 200 ?
      $.Deferred().reject( data ) :
      data;
  })
  .fail(function(data) {
    if ( data.responseCode )
      console.log( data.responseCode );
  });
}

xhr_get('/index').done(function(data) {
  // will not run if json returned from ajax has responseCode other than 200
});

在此处阅读有关 $.Deferred 的更多信息:http://api.jquery.com/category/deferred-object/

Read more about $.Deferred here: http://api.jquery.com/category/deferred-object/

注意:从 jQuery 1.8 开始，pipe 已被弃用，而是以完全相同的方式使用 then.

NOTE: As of jQuery 1.8, pipe has been deprecated in favor of using then in exactly the same way.