用Ajax如何驗證郵箱、用戶名的唯一性

 <script type="text/javascript">
 $(function () { 
 $("#txtEmail").blur(function () {
 $.ajax({
 type: "post",
 url: "reg.ashx?email=" + $.trim($("#txtEmail").val()) + "&d=" + (+new Date()),
 success: function (data) {
 var vCount = parseInt(data);
 if (vCount == 0) {
 alert("郵箱可以使用");
 }
 else {
 alert("郵箱已經被占用");
 }
 }
 });
 });
 $("#checkpwd").blur(function () {
 return CheckPwd();
 });
 });
 function CheckPwd()
 {
 var bCheck = true;
 if ($.trim($("#pwd").val()) != $.trim($("#checkpwd").val()))
 {
 alert("兩次密碼輸入不一致");
 bCheck = false;
 }
 return bCheck;
 }
 </script>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace WebT1.Ti.html2
{
 /// <summary>
 /// reg 的摘要說明
 /// </summary>
 public class reg : IHttpHandler
 {
 public void ProcessRequest(HttpContext context)
 {
 if (context.Request["email"] != null)
 {
 string strEmail = context.Request["email"];
 List<UserModel> lstUser = DataService.GetUserList();
 var v = lstUser.Where(p => p.Email == strEmail);
 int iCount = 0;
 if (v.Count() > 0)
 {
 iCount = 1;
 }
 context.Response.ContentType = "text/plain";
 context.Response.Write(iCount.ToString());
 }
 }
 public bool IsReusable
 {
 get
 {
 return false;
 }
 }
 }
 public class DataService
 {
 /// <summary>
 /// 模擬已注冊用戶數據
 /// </summary>
 public static List<UserModel> GetUserList()
 {
 var list = new List<UserModel>();
 list.Add(new UserModel() { Email = "t1@demo.com" });
 list.Add(new UserModel() { Email = "t2@demo.com" });
 list.Add(new UserModel() { Email = "t3@demo.com" });
 list.Add(new UserModel() { Email = "t4@demo.com" });
 list.Add(new UserModel() { Email = "t5@demo.com" });
 return list;
 }
 }
 public class UserModel
 {
 public string Email { get; set; }
 }
}