javascript实现Ajax代码

function AjaxObject() {
this.req = null;
this.getRequest = function() {
if (window.ActiveXObject) {
this.req = new ActiveXObject("Microsoft.xmlhttp");
} else if (window.XMLHttpRequest) {
this.req = new XMLHttpRequest();
}
}
this.sendRequest = function(url, params, Method) {
if (!Method) {
Method = "POST";
}
this.getRequest();
this.req.onreadystatechange = this.showData;
this.req.open(Method, url, true);
this.req.setRequestHeader("Content-Type",
"application/x-www-form-urlencoded");
this.req.send(params);
}
this.showData = function() {
}

}