// 注册：检测帐号是否存在
var ajax=new AJAXRequest;
function tryUser(userid)
{
    var um = document.getElementById("userid_mag");
    if(userid.length < 2)
    {
        um.innerHTML = "请输入帐号";
        return;
    }
    um.innerHTML = "检测中，请稍后...";
	   ajax.get
	   (
	      "Ajax.aspx?type=tryuser&user="+encodeURI(userid),
	      function(obj)
	        {
	            if(obj.responseText=="0")
				    um.innerHTML = "恭喜，该帐号可用";
			    else
			        um.innerHTML = "对不起，该帐号已经有人注册，请换一个";
		    }
	   );
}