Generic Handler

//Handler Class
1)Include js file

2) Add HTTP Handler
<%@ WebHandler Language="C#" Class="Handler" %>

using System;
using System.Web;

public class Handler : IHttpHandler {
   
    public void ProcessRequest (HttpContext context) {
        context.Response.ContentType = "text/plain";
        if (context.Request.QueryString["str"] != null)
        {
            string str = context.Request.QueryString["str"].ToString();
            context.Response.Write('1');
        }
    }

    public bool IsReusable {
        get {
            return false;
        }
    }

}

3) In code behind file
<script type="text/javascript" language="javascript" src="jquery-1.4.2.min.js"></script>
    <script language="javascript" type="text/javascript">
        function callhandler()
        {
      
            var str='Called';
            var param='str='+escape(str);
            $.ajax({
                   type:'GET',
                   url:'Handler.ashx',
                   data:param,
                   success:function(returnResponse)
                   {
                   
                         alert(returnResponse);
               
                  
                   }
           
            });
       
       
        }

    </script>

4) in Code behind file i.e. when you want to call the function write
protected void Page_Load(object sender, EventArgs e)
    {
        Button1.Attributes.Add("onclick", "javascript:callhandler()");
    }