求一段AJAX判断用户名是否存在?
我正在学习ASP.NET,想请大家教下我如何在注册页面做一段AJAX代码,我做好了注册页面
Register.aspx想在里面用AJAX实现无刷新的验证用户名是否存在,用的工具是vs2005
在线等~~~~~~

------解决方案--------------------
asp方法: 注册页
<script language = "JavaScript ">
function checkName(){
if (form.UserName.value== " "){
alert( "请输入名称! ");
return false;
}else{
var NameStr=form.UserName.value
var xmlhttp = new ActiveXObject( "Microsoft.XMLHTTP ");
xmlhttp.open( "POST ", "t.asp?uName= "+NameStr, false);
xmlhttp.send();
alert (xmlhttp.ResponseText)
//xmlhttp.readystate=4(没有任何数值时)
if(xmlhttp.ResponseText==1){
form.submit2.disabled=false;
alert( "可以注册! ");
}else{
alert( "用户名已经存在！ ");
}
}
}
</script>
<form name= "form " method= "get " action= " ">
<input name= "UserName " type= "text " id= "UserName " size= "25 " maxlength= "255 ">
<font color= "#ff6600 "> * </font>
<input type= "button " value= "检测用户名 " onclick= "checkName() ">
<input type= "submit " name= "submit2 " value= "注册 " id= "submit2 " disabled>
</form>
==============以上考虑到无输入字符不能验证,二是验证通过后才能提交
t.asp
<!--#include file= "Conn.asp " -->
<%
Set rs = Server.CreateObject ( "ADODB.Recordset ")
SQL = "Select * from users where username= ' "&trim(Request( "uName "))& " ' "
rs.Open SQL,conn,1,1
if rs.eof and rs.bof then
Response.write 1
end if
rs.close:set rs=nothing
%>