ajax初始化代码

//初始xmlHttp
function createXMLHttpRequest(){
var xmlHttp;
if (window.XMLHttpRequest){// code for IE7+, Firefox, Chrome, Opera, Safari
xmlHttp=new XMLHttpRequest();
}else{// code for IE6, IE5
xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
}
return xmlHttp;
}
//调用函数
function startRequest(){
var xmlHttp = createXMLHttpRequest();
var url="http://blog.189pt.com/?random="+ Math.random();
xmlHttp.open("GET",url,false);
xmlHttp.onReadyStateChange = function() {
if(xmlHttp.readyState==4){
if(xmlHttp.status==200){
//method
}
xmlHttp.send(null);
}
//执行
startRequest()