Asynchronous Requests with JavaScript and Ajax

An anonymous reader writes "I rarely read an entire article about a single object, especially one that is this simple. However, you will use this object over and over again in each page and application that you write that uses Ajax. This article shows you how to create XMLHttpRequest instances in a cross-browser way, construct and send requests, and respond to the server."

Comments

overriding the constructor

[ydnar]

With JavaScript, the object that is returned by the newoperator is the return value of the constructor. Which means you can set/override pretty much any object/property with a pseudo-constructor that returns any arbitrary object (class).

Adding XMLHttpRequest to Internet Explorer:

if( typeof window.XMLHttpRequest == "undefined" ) {
    window.XMLHttpRequest = function() {
        var types = [
            "Microsoft.XMLHTTP",
            "MSXML2.XMLHTTP.5.0",
            "MSXML2.XMLHTTP.4.0",
            "MSXML2.XMLHTTP.3.0",
            "MSXML2.XMLHTTP"
        ];

        for( var i = 0; i < types.length; i++ ) {
            try {
                return new ActiveXObject( types[ i ] );
            } catch( e ) {}
        }

        return undefined;
    }
}

y