Extending an ActiveXObject in javascript

Question

I want to add some functionality track certain calls to ActiveX object methods in javascript.

I usually create my activeX object like this: var tconn = new ActiveXO

Answer 1

Thank you very much for your wrapper. With your help I was able to create a xmlrequest detector for IE and FF and the rest.

I have added a version (combined from another example) that works for FF , IE and the rest of the gang,

if(window.XMLHttpRequest)
{
var XMLHttpRequest = window.XMLHttpRequest;

// mystery: for some reason, doing "var oldSend = XMLHttpRequest.prototype.send;" and 
//  calling it at the end of "newSend" doesn't work...
var startTracing = function () {
    XMLHttpRequest.prototype.uniqueID = function() {
        // each XMLHttpRequest gets assigned a unique ID and memorizes it 
        //  in the "uniqueIDMemo" property
        if (!this.uniqueIDMemo) {
            this.uniqueIDMemo = Math.floor(Math.random() * 1000);
        }
        return this.uniqueIDMemo;
    }

    // backup original "open" function reference
    XMLHttpRequest.prototype.oldOpen = XMLHttpRequest.prototype.open;

    var newOpen = function(method, url, async, user, password) {
        console.log("[" + this.uniqueID() + "] intercepted open (" + 
                    method + " , " + 
                    url + " , " + 
                    async + " , " + 
                    user + " , " + 
                    password + ")");
        this.oldOpen(method, url, async, user, password);
    }

    XMLHttpRequest.prototype.open = newOpen;

    // backup original "send" function reference
    XMLHttpRequest.prototype.oldSend = XMLHttpRequest.prototype.send;

    var newSend = function(a) {
        console.log("[" + this.uniqueID() + "] intercepted send (" + a + ")");
        var xhr = this;
        var onload = function() { 
            console.log("[" + xhr.uniqueID() + "] intercepted load: " + 
                    xhr.status + 
                    " " + xhr.responseText); 
        };

        var onerror = function() { 
            console.log("[" + xhr.uniqueID() + "] intercepted error: " + 
                    xhr.status); 
        };

        xhr.addEventListener("load", onload, false);
        xhr.addEventListener("error", onerror, false);

        this.oldSend(a);
    }
    XMLHttpRequest.prototype.send = newSend;
}


startTracing();
}
else if (window.ActiveXObject) {
var ActualActiveXObject = ActiveXObject;

var ActiveXObject = function(progid) {
    var ax = new ActualActiveXObject(progid);

    if (progid.toLowerCase() == "msxml2.xmlhttp") {

        var o = {
            _ax: ax,
            _status: "fake",
            responseText: "",
            responseXml: null,
            readyState: 0,
            status: 0,
            statusText: 0,
            onReadyStateChange: null
        };
        o._onReadyStateChange = function() {
            var self = o;
            return function() {
            self.readyState   = self._ax.readyState;
            if (self.readyState == 4) {
                self.responseText = self._ax.responseText;
                self.responseXml  = self._ax.responseXml;
                self.status       = self._ax.status;
                self.statusText   = self._ax.statusText;
            }
                if (self.onReadyStateChange) self.onReadyStateChange();
            }
        }();
        o.open = function(bstrMethod, bstrUrl, varAsync, bstrUser, bstrPassword) {
            console.log("intercepted open (" + 
                bstrMethod + " , " + 
                bstrUrl + " , " + 
                varAsync + " , " + 
                bstrUser + " , " + 
                bstrPassword + ")");
            varAsync = (varAsync !== false);
            this._ax.onReadyStateChange = this._onReadyStateChange
            return this._ax.open(bstrMethod, bstrUrl, varAsync, bstrUser, bstrPassword);
        };
        o.send = function(varBody) {
            return this._ax.send(varBody);
        };
    }
    else
        var o = ax;
    return o;
}
}