using System;

using System.Collections.Generic;

using System.Data;

using System.Data.SqlClient;

using System.Linq;

using System.ServiceModel.Web;

using System.Text;

using System.Web;

using System.Web.Script.Serialization;

using System.Web.Script.Services;

using System.Web.Services;

using System.Web.UI.WebControls;

[WebService(Namespace = "http://tempuri.org/")]

[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.

[System.Web.Script.Services.ScriptService]

public class WebService : System.Web.Services.WebService

{

   [WebMethod]

    [ScriptMethod(ResponseFormat = ResponseFormat.Json, UseHttpGet = true)]

    public void GetStores(string deliveryStartTime, string deliveryEndTime, bool is20To22 = false, string cityPOSCodePrefix = "")

    {

        var storeListJson = new StringBuilder();

        //

        var storeList = GetStoreList(deliveryStartTime, deliveryEndTime, is20To22, cityPOSCodePrefix);

        storeListJson.Append("[");

        foreach (var store in storeList)

        {

            string format = "{{\"Value\":\"{0}\", \"Text\":\"{1}\"}}";

            storeListJson.Append(string.Format(format, store.Value.ToString(), store.Text.ToString()));

            storeListJson.Append(",");

        }

        storeListJson.Remove(storeListJson.Length - , );

        storeListJson.Append("]");

        //

        Context.Response.Clear();

        Context.Response.ContentType = "text/json; charset=utf-8";

        //Context.Response.AddHeader("content-disposition", "attachment; filename=export.json");

        //Context.Response.AddHeader("content-length", storeListJson.Length.ToString());

        Context.Response.Flush();

        Context.Response.Write(storeListJson);

    }
 }

var url = "/webservice.asmx/GetStores?cityPOSCodePrefix=" + cityPOSCodePrefix + "&deliveryStartTime=" + deliveryStartTime

                + "&deliveryEndTime=" + deliveryEndTime + "&is20To22=" + is20To22;

$.ajax({

                url: url,

                type: 'get',

                async: false,

                contentType: 'text/json; charset=utf-8',

                success: function (result) {

                    //alert(result.d[0]);

                    var storeListString = "";

                    var storeLiValueStart = "<li style=\"float: left; margin-left: 40px; margin-top: 8px; width: 120px; border-radius: 8px; background-color: #FFF; border: 2px solid rgb(0,119,175);color:#0077af; padding: 4px 0px; text-align: center; cursor: pointer\" id=\"";

                    var storeLiValueEndAndTextStart = "\">";

                    var storeLiTextEnd = "</li>";

                    for (var i = ; i < result.length; i++) {

                        storeListString += storeLiValueStart;

                        storeListString += result[i].Value;

                        storeListString += storeLiValueEndAndTextStart;

                        storeListString += result[i].Text;

                        storeListString += storeLiTextEnd;

                    }

                    $("#storeListTest").html(storeListString);

                }

    <webServices>

      <protocols>

        <add name="HttpGet" />

      </protocols>

    </webServices>