jquery判断用户名称是否存在

/// <reference path="../jquery-1.3.2-vsdoc.js" />
$(document).ready(function(){
checkConfirm();
});
//验证用户名是否存在
function checkConfirm() {
    $("#TextBox_college_english_name").blur(function() {
        var gradename = $(this).val();
        var changeUrl = "../../handlers/cms/GetCollegeName.ashx?college_english_name=" + gradename;
        $.get(changeUrl, function(str) {

            if (str == '1') {
                alert("已经存在英文名称为" + $("#TextBox_college_english_name").val() + "的院校，请查证！");
                $("#TextBox_college_english_name").val("");
            } else {
                $("#gradeInfo").html("");
            }
        })
        return false;
    })
}

ashx页面代码

using System;
using System.Collections;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Xml.Linq;

using Study.BLL.College_BLL;
namespace Study.Web.handlers.cms
{
    /// <summary>
    /// $codebehindclassname$ 的摘要说明
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    public class GetCollegeName : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/plain";
           
            string username = context.Request.QueryString["college_english_name"].ToString();
            BLL_College bll_college = new BLL_College();
            DataTable dt = bll_college.GetCollegeEnglishName(username);
            if (dt.Rows.Count > 0)
            {
                context.Response.Write("1");
            }
            else
            {
                context.Response.Write("0");
            }
           
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}