How to detect if the browser accepts xmlhttprequest events?

Question

It is the following, gurizada, to make my object compatible with old browsers (if not swear me) I created a new problem. It is difficult to deviate the path according to the browser version because it was not so standardized, the browsers accepted one resource and another not, so I did the following:

var reqEngatilhar = function(){
    este.concluido = false;
    timeoutId = setTimeout(reqTimeout, este.timeout);
    if(este.Request.hasOwnProperty("onload")){
        este.Request.addEventListener("error", reqErro, true);
        este.Request.addEventListener("progress", reqMon, false);
        este.Request.addEventListener("abort", reqAbort, false);
        este.Request.addEventListener("load", reqFim, false);
        console.log("$Http reqEngatilhar usando eventos...");
    } else {
        este.Request.onreadystatechange = function (e) { reqSwitch(e); };
        console.log("$Http reqEngatilhar usando onreadystatechange...");
    }
}

This little function defines the events within my object when it changes the state of the xmlhttprequest request (where this=this outside of the function). But some browsers do not accept events via addeventlistener, so it sets onreadystatechange that will make the "distribution" by calling the right function.

The problem is the test this.Request.hasOwnProperty("onload") which is working only for Safari (my site only opens in Safari kkkkk).

So I ask: what is the correct (or best possible) way to detect if the browser accepts xmlhttprequest events via addeventlistener?

Answer 1

Do so:

if(window.XMLHttpRequest && !(window.ActiveXObject)) {
    try {
        req = new XMLHttpRequest();
    } catch(e) {
        req = false;
    }
} else if(window.ActiveXObject) { // Se for IE usa o control ActiveX
    try {
        req = new ActiveXObject("Msxml2.XMLHTTP");
    } catch(e) {
        try {
            req = new ActiveXObject("Microsoft.XMLHTTP");
        } catch(e) {
            req = false;
        }
    }
}
return req;

Full reference: https://github.com/pmcfernandes/r/blob/master/Linq.js