XHR 同步调用在 Chrome 中失败.脚本不等待 xhr 响应 [英] XHR sync calls failing in Chrome. Script not waiting for the xhr response

问题描述

问题:在 Chrome 中工作时，脚本没有等待同步 xhr 响应.在 FireFox/IE 中工作正常.也使用了 onreadyStateHandlers，但仍然在收到响应之前执行其他代码.

Issue: While working in Chrome, script not waiting for the Synchronous xhr response. Working fine in FireFox/IE. Have used onreadyStateHandlers as well, but still, before the response is received the other codes are executed.

function callingScript()
{ var a=callServer();
   alert(a);//Here a is showing undefined while executing in chrome. 
            But in FF/IE its waiting for the response and then alerts a with response. 
}

function callServer()
{
 var response;
 var httpRequest = new XMLHttpRequest();
 httpRequest.open("POST","abc",false);
 httpRequest.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
 httpRequest.onreadystatechange = function() 
   {       
        if (httpRequest.readyState != 4)  
           {return; }

        if (httpRequest.status != 200)    
               {response=httpRequest.status;}
        else   {response=httpRequest.responseText;}

   };
 httpRequest.send(data);
 return response;

 }

请分享您的想法！！

推荐答案

函数 callServer() 不会等待请求得到响应.使用回调来解决这个问题:

the function callServer() does not wait for the request to be responded. use a callback to solve this problem:

function callingScript()
{ callServer(function(response) {
      alert(response);
  });
}

function callServer(callback)
{
 var response;
 var httpRequest = new XMLHttpRequest();
 httpRequest.open("POST","abc",false);
 httpRequest.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
 httpRequest.onreadystatechange = function() 
   {       
        if (httpRequest.readyState != 4)  
           {return; }

        if (httpRequest.status != 200)    
               {response=httpRequest.status;}
        else   {response=httpRequest.responseText;}

        callback(response);
   };
 httpRequest.send(data);
 return response;

 }

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