ajax.js

var Ajax = new Object();

Ajax.getXHR = function() {
    var http;
    try {
        http = new XMLHttpRequest;
            Ajax.getXHR = function() {
                return new XMLHttpRequest;
            };
    }
    catch(e) {
        var msxml = [
            'MSXML2.XMLHTTP.3.0',
            'MSXML2.XMLHTTP',
            'Microsoft.XMLHTTP'
        ];
        for (var i=0, len = msxml.length; i < len; ++i) {
            try {
                http = new ActiveXObject(msxml[i]);
                Ajax.getXHR = function() {
                    return new ActiveXObject(msxml[i]);
                };
                break;
            }
            catch(e) {}
        }
    }
    return http;
};

Ajax.handleReadyState = function(o, callback) {
    if (o && o.readyState == 4 && o.status == 200) {
        if (callback) {
            callback(o);
        }
    }
};


Ajax.call = function(method, uri, callback, postData) {
    var http = Ajax.getXHR();
    http.onreadystatechange = function(){Ajax.handleReadyState(http, callback)};
    http.open(method, uri, true);
    //if(method=='POST'){http.setRequestHeader('Content-type','application/x-www-form-urlencoded; charset=utf-8');}
    http.send(postData || null);
    return http;
};