XMLHtt prequest始终在呼唤＆QUOT;负载＆QUOT;事件侦听器，即使在响应具有错误状态 [英] XMLHttpRequest is always calling "load" event listener, even when response has error status

问题描述

我用FORMDATA到阿贾克斯的文件上传。上传作品，但问题是，错误回调是永远不会被调用。甚至当我的HTTP响应是一个500内部服务器错误（测试此我调整服务器与500响应），加载回调函数。

I'm using FormData to ajax a file upload. The upload works, but the problem is that the "error" callback is never invoked. Even when my HTTP response is a 500 internal server error (to test this I tweak server to respond with 500), the "load" callback is invoked.

function upload_image() {
    var form = document.getElementById('upload_image_form');
    var formData = new FormData(form);

    var xhr = new XMLHttpRequest();
    xhr.addEventListener("load", function(e) {
        alert("Success callback");
    }, false);
    xhr.addEventListener("error", function(e) {
        alert("Error callback");
    }, false);
    xhr.open("POST", "/upload_image");
    xhr.send(formData);
}

任何想法？我在Chrome测试这个。

Any ideas? I'm testing this on Chrome.

推荐答案

此设置应该更适合你的需求：

This setup should work better for your needs:

var req = new XMLHttpRequest();
req.open('POST', '/upload_image');
req.onreadystatechange = function (aEvt) {
  if (req.readyState == 4) {
     if(req.status == 200)
      alert(req.responseText);
     else
      alert("Error loading page\n");
  }
};
req.send(formData);

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