从未调用过 Javascript 函数 onload [英] Javascript function onload never called

问题描述

我希望得到一个带有来自 webservice 的 get 请求的 json 文件，并且我有一个跨域请求"，所以我选中了withCredentials"，然后我使用 onload 函数将 json 的内容显示在控制台.

I wish to get a json file with a get request from a webservice, and I have a "cross origin request", so I check "withCredentials", and then I use the onload function to display the content of the json on the console.

function createCORSRequest(method, url) {
  var xhr = new XMLHttpRequest();

  if ("withCredentials" in xhr) {
    xhr.open(method, url, true);
    console.log("withCredentials is true");

    xhr.onload = function() {
      console.log('ok');
      if (xhr.status >= 200 && xhr.status < 400) {
        data.forEach(card => {
          console.log(card.nameEnglish1);
        })
      } else {
        console.log('error');
      }
    };

    xhr.onerror = function() {
      console.log('There was an error!');
    };

  } else if (typeof XDomainRequest != "undefined") {
    xhr = new XDomainRequest();
    xhr.open(method, url);
  } else {
    xhr = null;
  }
  return xhr;
}

var xhr = createCORSRequest('GET', 'http://192.168.42.176:8080/batch-recup-mtg-0.0.1-SNAPSHOT/mtg/cards/search?setCode=AKH');
if (!xhr) {
  throw new Error('CORS not supported');
}

但是什么也没发生，我的 onload 函数从来没有被调用过，我也没有任何错误.我确定网络服务正在运行，因为我在浏览器中尝试过.您知道为什么从不调用 onload 函数吗?

But nothing happen, my onload function is never called, and I don't have any error. I'm sure that the webservice is working because I tried it in my browser. Do you have any idea why the onload function is never called?

EDIT : console.log("withCredentials is true"); 显示，但 console.log('ok'); 不是

EDIT : console.log("withCredentials is true"); is displayed, but console.log('ok'); isn't

推荐答案

您需要

xhr.send();

function createCORSRequest(method, url) {
  var xhr = new XMLHttpRequest();

  if ("withCredentials" in xhr) {
    xhr.open(method, url, true);
    console.log("withCredentials is true");

    xhr.onload = function() {
      console.log('ok');
      if (xhr.status >= 200 && xhr.status < 400) {
        data.forEach(card => {
          console.log(card.nameEnglish1);
        })
      } else {
        console.log('error');
      }
    };

    xhr.onerror = function() {
      console.log('There was an error!');
    };

    // added send call here:
    xhr.send();

  } else if (typeof XDomainRequest != "undefined") {
    xhr = new XDomainRequest();
    xhr.open(method, url);
  } else {
    xhr = null;
  }
  return xhr;
}

var xhr = createCORSRequest('GET', 'http://google.com/');
if (!xhr) {
  throw new Error('CORS not supported');
}

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