Simple Ajax Class

// Request class
Request = function(){
	Request = window.XMLHttpRequest?new XMLHttpRequest():window.ActiveXObject?new ActiveXObject("Microsoft.XMLHTTP"):false;
	Request.fn = function(fn){
		if(typeof fn=='string')return new Function(fn);
		if(typeof fn=='function')return fn;
		if(typeof fn=='undefined')return new Function();
	};
	Request.config = {
		'xml' : false,
		'404' : 'File not found'
	};
 
	Request.success = false;
	Request.loading = false;
	Request.error = false;
 
	Request.submit = function(obj){		
		if(Request){
			Request.onreadystatechange = function(){
				if(Request.status==200){
					if(Request.readyState==4){
						Response = Request.config['xml']?Request.responseXml:Request.responseText;
						if(Request.success){
							Request.fn(Request.success).call(this, Response, Request);
						} else {
							Request.fn(obj.success).call(this, Response, Request);
						}
					} else {
						if(Request.success){
							Request.fn(Request.loading).call(this, Request);
						} else {
							Request.fn(obj.loading).call(this, Request);
						}
					}
				} else {
					if(Request.success){
						Request.fn(Request.error).call(this, Request.config['404']);
					} else {
						Request.fn(obj.error).call(this, Request.config['404']);
					}
				};
			}
 
			Request.open("GET", obj.url, true);
			Request.send(null);
		} else obj.error.call(this, Request);
	};
 
	return Request;
};
 
// Eval code
var req = new Request;
req.submit({
	url : 'plik.xml',
	xml : false,
	success : function(res, req){
		document.getElementById('p2').innerHTML = res;
	},
	loading : function(){ console.log('loading...'); },
	error : function(err){ console.log(err); }
});