Ajax中哪些框架？

function check_sn_a(check)
{
if(check.readyState!=4 && check.status!=200)
return false ;

var t=check.responseText;
if(t=="false")
{
document.getElementById('sn_text').innerHTML="*宝箱密码不存在或者已经失效";
return false;
}
else
{
document.getElementById('sn_text').innerHTML=" 输入正确";
return true;
}

}

function chk_sn()
{

if (document.getElementById('input_sn').value=="")
{
document.getElementById('sn_text').innerHTML="*请您输入奇山卡片上的18位密码";
return false ;
}
else
{
check=window.ActiveXObject ? new ActiveXObject("Microsoft.XMLHTTP"):new XMLHttpRequest();
check.onreadystatechange=ck_sn;
var sn=document.getElementById('input_sn').value;
var url="check_sn.php?sn="+sn;
check.open("GET",url,true);
check.send(null);
return check_sn_a (check) ;
}
}