<div> <input id="txtName" type="text" /><input type="button" value="查看用户名是否存在" id="btn" onclick="JudgeUserName();" /> <div id="showResult" style="float:left">div> div>

<script type="text/javascript" src="CSS/jquery-1.3.2.js"></script> <script type="text/javascript"> function JudgeUserName() { $.ajax({ type:"GET", url:"AjaxUserInfoModify.aspx", dataType:"html", data:"userName="+$("#txtName").val(), beforeSend:function(XMLHttpRequest) { $("#showResult").text("正在查询"); //Pause(this,100000); }, success:function(msg) { $("#showResult").html(msg); $("#showResult").css("color","red"); }, complete:function(XMLHttpRequest,textStatus) { //隐藏正在查询图片 }, error:function() { //错误处理 } }); } </script>

protected void Page_Load(object sender, EventArgs e) { string userName = Request.QueryString["userName"].ToString (); if (userName == "James Hao") { Response.Write ("用户名已经存在！"); } else { Response.Write ("您可以使用此用户名！"); } }