open(method,url,async);

send(string);

request.open("GET","get.php",true);

request.send();

request.open("POST","post.php",true);

request.setRequestHeader("Content-type","application/x-www-form-unlencoded");//设置头信息，写在中间

request.send("name=Judy&sex=female");

取得响应：

var request = new XMLHttpRequest();

request.open("GET","get.php",ture);

request.send();

request.onreadystatechange = function(){

if(request.readyState ===4&& request.status===200)

//执行一些事情request.responseText

} }