Consuming asp.net webservice using jquery

Created a simple way to consume asp.net webservice using jquery. The webservice gets data from sql database and return result back as json data type.

Hope this help!

----------default.aspx------------------

<button type="button" onclick="button_onclick">Click</button>
<input type="text" id="txt_username" />
<input type="text" id="txt_email" />

----------main.js-----------------------

<script type="text/javascript">
  function button_onclick() {
        $.ajax({
            type: "POST",
            url: "../webservice.asmx/checkUserExist",
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            data: "{username:'" + $("input#txt_username").val() + "',email:'" + $("input#txt_email").val() + "'}",
            timeout: 10000,
            success: function (result) {
                if (result.d != null) {
                   var value = eval("(" + result.d + ")");
                }
		alert(value[0].result);
            },
            error: function (evt) {
                alert(evt.status + "(" + evt.statusText + ")");
            }
        });
  };
</script>

--------webservice.asmx------------------

Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.ComponentModel
Imports System.Data
Imports System.IO
Imports System.Data.SqlClient
Imports System.Web.Script
Imports System.Web.Script.Serialization
Imports System.Web.Script.Services

' To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
<System.Web.Script.Services.ScriptService()> _
<System.Web.Services.WebService(Namespace:="http://domain.com")> _
<System.Web.Services.WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _
<ToolboxItem(False)> _
Public Class OPResume
    Inherits System.Web.Services.WebService
    Dim sql As String = String.Empty
    Dim rs As SqlDataReader

    <WebMethod()> _
    Public Function checkUserExist(ByVal username As String, ByVal email As String) As String
        Dim param(1) As SqlParameter
	Dim result as string = string.empty
  
        sql = "sp_checkUserExist"
        param(0) = New SqlParameter("@username", username)
        param(0).SqlDbType = SqlDbType.VarChar

        param(1) = New SqlParameter("@email", email)
        param(1).SqlDbType = SqlDbType.VarChar

        Using db As New Database
            rs = db.ExecuteReader(sql, param)
	    if rs.hasrow() then
		rs.read()
		result("[{")
            	result("""result"":""")
            	result(rs("result").ToString)
            	result("""}]")
	    end if
        End Using

        return result
    End Function
End Class