ajax：异步&同步

ajax：异步&同步传输

//创建对象：XMLHttpRequest();
xmlhttp=new XMLHttpRequest();

//服务器响应
xmlhttp.onreadystatechange=function()
{
    if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
        document.getElementById("myDiv").innerHTML=xmlhttp.responseText;
    }
}

//向服务器发送请求
xmlhttp.open("GET","ajax_info.txt",true);
xmlhttp.send();
/*POST请求
*xmlhttp.open("POST","/try/ajax/demo_post2.php",true);
*xmlhttp.setRequestHeader("Content-type","application/x-www-*form-urlencoded");
*xmlhttp.send("fname=Henry&lname=Ford");
*/