Auto Complete TextBox in asp.net

In .aspx file add these line to head section:

<link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.1/themes/base/jquery-ui.css" rel="stylesheet" type="text/css"/>

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.1/jquery-ui.min.js"></script>

<script type="text/javascript">

$(document).ready(function() {

SearchText();

});

function SearchText() {

$(".autosuggest").autocomplete({

source: function(request, response) {

$.ajax({

type: "POST",

contentType: "application/json; charset=utf-8",

url: "NewEmployee.aspx/GetAutoCompleteData",

data: "{'username':'" + document.getElementById('txtEmail').value + "'}",

dataType: "json",

success: function(data) {

response(data.d);

},

error: function(result) {

alert("Error");

}

});

}

});

}

</script>

In page body:

<input type="text" id="txtEmail" class="autosuggest" />

In .cs file Add these lines:

[WebMethod]

    public static List<string> GetAutoCompleteData(string username)

    {

        string strCon = ConfigurationManager.ConnectionStrings["IRTConnectionString"].ConnectionString;

        List<string> result = new List<string>();

        using (SqlConnection con = new SqlConnection(strCon))

        {

            using (SqlCommand cmd = new SqlCommand("SELECT username FROM t_Employee WHERE username LIKE '%'+@SearchText+'%'", con))

            {

                con.Open();

                cmd.Parameters.AddWithValue("@SearchText", username);

                SqlDataReader dr = cmd.ExecuteReader();

                while (dr.Read())

                {

                    result.Add(dr["username"].ToString());

                }

                return result;

            }

        }

    }

You need to add this reference 'System.Web.Services'.