jQuery：处理失败的AJAX请求的后备 [英] jQuery: Handle fallback for failed AJAX Request

问题描述

jQuery能否为失败的AJAX调用提供后备？这是我的尝试：

Can jQuery provide a fallback for failed AJAX calls? This is my try:

function update() {
    var requestOK = false;

    $.getJSON(url, function(){
        alert('request successful');
        requestOK = true;
    });

    if (!requestOK) {
        alert('request failed');
    }
}

。 getJSON（）方法被调用，我获得消息请求失败，在回调函数之前有机会设置requestOK变量。我认为这是因为代码并行运行。有办法处理这种情况吗？我想到了链接或某种方式等待AJAX​​请求，包括它的回调函数。但是怎么样？

Unfortunately, even if the callback function of the $.getJSON() method is called, i get the message 'request failed', before the callback function has the opportunity to set the requestOK variable. I think it's because the code runs in parallel. Is there a way to handle such situations? I thought about chaining or some way of waiting for the AJAX request, including its callback function. But how? Does anyone know how to do that?

推荐答案

您需要使用底层 $。ajax 调用，或 ajaxError function。这里是$ .ajax方法：

You will need to either use the lower level $.ajax call, or the ajaxError function. Here it is with the $.ajax method:

function update() {
  $.ajax({
    type: 'GET',
    dataType: 'json',
    url: url,
    timeout: 5000,
    success: function(data, textStatus ){
       alert('request successful');
    },
    error: function(xhr, textStatus, errorThrown){
       alert('request failed');
    }
  });
}

EDIT > timeout 到 $。ajax 调用并将其设置为五秒。

EDIT I added a timeout to the $.ajax call and set it to five seconds.

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