A simple AJAX class.

simple_ajax.js

SimpleAjax = function(url, method, content){
	this.r = null;
	this.url = url;
	this.method = method;
	this.content = content;
	this.header = {};
	this.header["Connection"] = "close";
	this.header["Content-type"] = "application/x-www-form-urlencoded";

	var self = this;

	if(window.XMLHttpRequest){
		this.r = new XMLHttpRequest();
	}else if(window.ActiveXObject){
		try {
			this.r = new ActiveXObject("Msxml2.XMLHTTP");
		} catch(e) {
			try{
				this.r = new ActiveXObject("Microsoft.XMLHTTP");
			} catch(e) {
			}
		}
	}

	this.When = function(http_status, func){
		if(!this.L)
			this.L=[];
		this.L[http_status] = func;
		return this;
	};

	this.SetHeader = function(name, value){
		this.header[name] = value;
		this.r.setRequestHeader(name, value);
		return this;
	};

	this.Send = function(){
		if(this.method != "post" && this.method != "get")
			this.method = "get";

		this.r.open(this.method, this.url, true);

		for(var h in this.header) {
			this.r.setRequestHeader(h, this.header[h]);
		}

		this.r.send(this.content);
	};

	if(this.r) this.r.onreadystatechange = function(){
		if(self.r.readyState == 4 && self.L[self.r.status] != null)
			self.L[self.r.status](self.r.responseText);
	};
};

Example 1:

var ajax = new SimpleAjax(url);

ajax.When(200, function(r){
   alert(r);
});

ajax.Send();

Example 2:

var ajax = new SimpleAjax(url).When(200, function(r){
   alert(r);
}).Send();