最近一直瘋狂寫聊天室，更新一堆有的沒的，發個小筆記。
var http = new XMLHttpRequest("Microsoft.XMLHTTP");
var url_='http://example.com/';
function connect(){
http.onreadystatechange = function(){
if (http.readyState==4){
if (http.status==200){
//Do Something.
}else{
//Connect Failed.
}
}
}
http.open("GET",url_,true);
http.send();
}
