编辑：

最近对此表示赞同，我不得不说我不再这样做。$.ajax返回a，promise因此您可以直接使用promise以更一致和更可靠的方式执行我在这里所做的几乎所有工作。

function customRequest(u,d) {
   var promise = $.ajax({
     type: 'post',
     data: d,
     url: u
   })
   .done(function (responseData, status, xhr) {
       // preconfigured logic for success
   })
   .fail(function (xhr, status, err) {
      //predetermined logic for unsuccessful request
   });

   return promise;
}

然后用法如下：

// using `done` which will add the callback to the stack 
// to be run when the promise is resolved
customRequest('whatever.php', {'somekey': 'somevalue'}).done(function (data) {
   var n = 1,
       m = 2;

   alert(m + n + data);
});

// using fail which will add the callback to the stack 
// to be run when the promise is rejected
customRequest('whatever.php', {'somekey': 'somevalue'}).fail(function (xhr, status, err) {
   console.log(status, err);
});

// using then which will add callabcks to the 
// success AND failure stacks respectively when 
// the request is resolved/rejected
customRequest('whatever.php', {'somekey': 'somevalue'}).then(
  function (data) {
     var n = 1,
         m = 2;

     alert(m + n + data);
  },
  function (xhr, status, err) {
     console.log(status, err);
  });

当然，我一直都这样做。您可以在实际的成功Callack中执行回调，也可以将回调分配为成功回调：

function customRequest(u,d,callback) {
   $.ajax({
     type: "post",
     url: u,
     data:d,
     success: function(data) {
        console.log(data); // predefined logic if any

        if(typeof callback == 'function') {
           callback(data);
        }
     }
  });
}

用法如下所示：

customRequest('whatever.php', {'somekey': 'somevalue'}, function (data) {
   var n = 1,
       m = 2;

   alert(m + n + data);
});