AJAX 核心三部曲

//建立物件
function createXMLHttpRequest(){
if(window.ActiveXObject){
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
else if(window.XMLHttpRequest){
xmlHttp = new XMLHttpRequest();
}
}

//前臺介面事件呼叫的函式
function checkName(){
createXMLHttpRequest();
xmlHttp.onreadystatechange = handleStateChange;
var sql = "UserReg.aspx?";
xmlHttp.open("GET",sql,true);
xmlHttp.send(null);
}

//和伺服器互動期間執行的函式
function handleStateChange(){
if(xmlHttp.readyState == 4){
if(xmlHttp.status == 200){
document.getElementById("divx").innerHTML = xmlHttp.responseText;
}
}
}