javascript - How to modify ActiveXObject JS constructor? - Stack Overflow

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I need to wrap an IE ajax request to notify me when it happens. ie i need to know when open is called on this:

var xhr = new ActiveXObject("Microsoft.XMLHTTP");

The only way to do that(i think) is to implement the ActiveXObject constructor to proxy open calls to the real constructor/object. Can you help me do that?

also: i dont need to create the actual xhr object, so please dont tell me to use X framework because its easy.

all i need to know is when open is called (not by my code) on an MS xhr object.

Thank you very much!

I need to wrap an IE ajax request to notify me when it happens. ie i need to know when open is called on this:

var xhr = new ActiveXObject("Microsoft.XMLHTTP");

The only way to do that(i think) is to implement the ActiveXObject constructor to proxy open calls to the real constructor/object. Can you help me do that?

also: i dont need to create the actual xhr object, so please dont tell me to use X framework because its easy.

all i need to know is when open is called (not by my code) on an MS xhr object.

Thank you very much!

• javascript
• ajax
• binding
• proxy

Share Improve this question Follow edited Apr 25, 2009 at 19:21 mkoryak asked Apr 16, 2009 at 15:54 mkoryakmkoryak 58k6464 gold badges203203 silver badges262262 bronze badges

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5 Answers 5

Sorted by: Reset to default 3 +100

Since the OP has posted a similar question, and I posted an answer which also happens to fit this question, he asked me to link to my answer, instead of repeating it here.

• Q: Extending an ActiveXObject in javascript
• A: A drop-in transparent wrapper for MSXML2.XMLHTTP

Perhaps you can try something like this:

XMLHttpRequest.prototype.real_open = XMLHttpRequest.prototype.open;

var your_open_method = function(sMethod, sUrl, bAsync, sUser, sPassword) { 
  alert('an XHR request has been made!');
  this.real_open(sMethod, sUrl, bAsync, sUser, sPassword); 
} 

XMLHttpRequest.prototype.open = your_open_method;

Of course, instead of the alert you can have your own tracking code. I tried it out and it works on 'plain javascript' requests and also requests made with jquery. I think it should work regardless of the framework that was used to make the request.

EDIT April 21 I don't really know how an ActiveXObject can be extended. My guess is that something like this should work:

XHR = new ActiveXObject("Microsoft.XMLHTTP");
var XHR.prototype.old_open = XHR.prototype.open;
var new_open = function(sMethod, sUrl, bAsync, sUser, sPassword) { 
  alert('an IE XHR request has been made!');
  this.old_open(sMethod, sUrl, bAsync, sUser, sPassword); 
} 

XHR.prototype.open = new_open;

Unfortunately (or maybe not) I don't have IE, so I can't test it. But give it a spin and let me know if it did the trick.

There is nothing "to get at real object" it is the real object!

Sounds like you are looking for something like this guy is doing....

http://www.adobepress./articles/article.asp?p=439600

document.write("<script type=\"text/javascript\" src=\"js/HTTP.js\"></script>");

function Ajax()
{
  this.toString = function() { return "Ajax"; }
  this.http = new HTTP();

  this.makeRequest = function(_method, _url, _callbackMethod)
  {
    this.request = (window.XMLHttpRequest)? new XMLHttpRequest(): new ActiveXObject("MSXML2.XMLHTTP");
    this.request.onreadystatechange = _callbackMethod;
    this.request.open(_method, _url, true);
    this.request.send(_url);
  }

  this.checkReadyState = function(_id, _1, _2, _3)
  {
    switch(this.request.readyState)
    {
      case 1:
        document.getElementById(_id).innerHTML = _1;
        break;
      case 2:
        document.getElementById(_id).innerHTML = _2;
        break;
      case 3:
        document.getElementById(_id).innerHTML = _3;
        break;
      case 4:
        return this.http.status(this.request.status);
    }
  }
}

This has always worked for me.

var xmlHttp;

function yourajaxfunction(str)
{ 
   xmlHttp=GetXmlHttpObject();
   if (xmlHttp==null){
      alert ("Browser does not support HTTP Request");
      return;
   }

   var url="yourserversidecodefile.php";
   url=url+"?q="+str;

   xmlHttp.onreadystatechange=stateChanged;
   xmlHttp.open("GET", url, true);
   xmlHttp.send(null);
}

function stateChanged() { 
   if (xmlHttp.readyState==4 || xmlHttp.readyState=="plete"){ 
      document.getElementById("txtHint").innerHTML=xmlHttp.responseText;
   } 
}

function GetXmlHttpObject(){
   var xmlHttp=null;

   try {
      // Firefox, Opera 8.0+, Safari
      xmlHttp=new XMLHttpRequest();
   }
   catch (E1) {
      //Internet Explorer
      try {
         xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
      }
      catch (E2) {
         xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
      }
   }

   return xmlHttp;
}

I remend you to use jQuery for AJAX . It's very small but very flexible and fast framework. Check out docs here.

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