基本用法：
var ajax = new AjaxObj(url);
ajax.addListener(200, function(r){
alert(r);
});
ajax.send();
也可以连续调用：
var ajax = new AjaxObj(url).addListener(200, function(r){
alert(r);
}).send();
另外还支持自定义的POST或GET方式请求，以及监视不同的HTTP状态码，自己看代码琢磨吧 :)
完整代码：
AjaxObj = 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.addListener = 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);
};
};
