function Foo() {
    this.site = "http://www.google.com";
    this.onready = function(text) {
        alert(text);
        // do response processing here
    }
    var xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    xmlhttp.open("GET", this.site, true);
    xmlhttp.onreadystatechange = function() { 
        if (xmlhttp.readyState == 4) {
            var text = xmlhttp.responseBody;
            this.onready(text);
            // Object doesn't support this property or method
        }
    }
    xmlhttp.send();
}

objFoo = new Foo();