using System.Web.Mvc;
using System.Web.Script.Serialization;

namespace Mvc4TwitterBootStrapTest.Controllers
{
    public class HomeController : Controller
    {
        [HttpGet]
        public ActionResult Index()
        {
            var array = new[]
                {
                     "Afghanistan",
                     "Albania",
                     "Algeria",
                     "American Samoa",
                     "Andorra",
                     "Angola",
                     "Anguilla",
                     "Antarctica",
                     "Antigua and/or Barbuda"
                };
            ViewBag.JsonString = new JavaScriptSerializer().Serialize(array);
            return View();
        }
    }
}

@{
    ViewBag.Title = "Index";    
}
<h2>
    Typeahead</h2>
@Html.TextBox("search", null, htmlAttributes:
                              new
                              {
                                  autocomplete = "off",
                                  data_provide = "typeahead",
                                  data_items = 8,
                                  data_source = @ViewBag.JsonString
                              })

<input autocomplete="off" data-items="8" data-provide="typeahead" 
data-source="[&quot;Afghanistan&quot;,&quot;Albania&quot;,&quot;Algeria&quot;,&quot;American Samoa&quot;,&quot;Andorra&quot;,&quot;Angola&quot;,&quot;Anguilla&quot;,&quot;Antarctica&quot;,&quot;Antigua and/or Barbuda&quot;]" 
id="search" name="search" type="text" value="" />

        public static MvcHtmlString TypeaheadFor<TModel, TValue>(
                this HtmlHelper<TModel> htmlHelper,
                Expression<Func<TModel, TValue>> expression,
                IEnumerable<string> source,
                int items = 8)
        {
            var jsonString = new JavaScriptSerializer().Serialize(source);
            return htmlHelper.TextBoxFor(
                expression,
                new
                {
                    autocomplete = "off",
                    data_provide = "typeahead",
                    data_items = items,
                    data_source = jsonString
                }
            );
        }

using System;
using System.Linq;
using System.Web.Mvc;
using System.Web.Script.Serialization;

namespace Mvc4TwitterBootStrapTest.Controllers
{
    public class HomeController : Controller
    {
        [HttpGet]
        public JsonResult GetNames(string term)
        {
            var array = new[]
                {
                     "Afghanistan",
                     "Albania",
                     "Algeria",
                     "American Samoa",
                     "Andorra",
                     "Angola",
                     "Anguilla",
                     "Antarctica",
                     "Antigua and/or Barbuda"
                };

            var results = array.Where(n =>
                n.StartsWith(term, StringComparison.OrdinalIgnoreCase));

            return Json(results.ToArray(), JsonRequestBehavior.AllowGet);
        }
    }
}

@{
    ViewBag.Title = "Index";
    var url = Url.Action("GetNames", "Home");
}
<h2>
    Typeahead</h2>
@Html.TextBox("search", null, htmlAttributes:
                              new
                              {
                                  autocomplete = "off",
                                  data_provide = "typeahead",
                                  data_items = 8
                              })
@section JavaScript
{
    <script type="text/javascript">
            $(function () {
                $('#search').typeahead({
                    source: function (term, process) {
                        return $.getJSON('@url', { term: term }, function (data) { return process(data); });
                    }
                });
            });
    </script>
}

AspNetCore.Unobtrusive.Ajax 

Unobtrusive Ajax Helpers (like MVC5 Ajax.BeignForm and Ajax.ActionLink) for ASP.NET Core 

Features

• Works with Upload file.
• Works with [AntiForgeryTokenValidation].
• Has [AjaxOnly] attribute to limit actions.
• Has httpRequest.IsAjaxRequest() extension method to check request is ajax and decide return PartialView or JSON result.
• Additional overloads for ease of use.
• Adds necessary JS script automatically when you use a Ajax Helpers and remove JS script when you no longer use it (Optional - is by default).
• Uses CDN url instead of Embedded script (Optional - isn't by default). 

USE [Coordinates]
GO
CREATE TABLE [dbo].[Coords2](
[top] [int] NULL,
[left] [int] NULL,
[width] [int] NULL,
[height] [int] NULL,
[text] [nvarchar](50) NULL,
[id] [uniqueidentifier] NULL,
[editable] [bit] NULL
) ON [PRIMARY]
GO

public class Coords
{
    public string top;
    public string left;
    public string width;
    public string height;
    public string text;
    public string id;
    public string editable;

    public Coords(string top, string left, string width, string height, string text, string id, string editable)
    {
        this.top = top;
        this.left = left;
        this.width = width;
        this.height = height;
        this.text = text;
        this.id = id;
        this.editable = editable;


    }
}

[WebMethod]
    public static List<Coords> GetDynamicContext(string entryId, string entryName)
    {
        List<Coords> CoordsList = new List<Coords>();

        string connect = "Connection String";
        using (SqlConnection conn = new SqlConnection(connect))
        {
            string query = "SELECT [top], [left], width, height, text, id, editable FROM  Coords2";
            using (SqlCommand cmd = new SqlCommand(query, conn))
            {
                conn.Open();
                using (SqlDataReader reader=cmd.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        CoordsList.Add(new Coords(reader["top"].ToString(), reader["left"].ToString(),
                                                  reader["width"].ToString(), reader["height"].ToString(),
                                                  reader["text"].ToString(), reader["id"].ToString(),
                                                  reader["editable"].ToString()));
                    }
                }
               
               conn.Close();
            }
        }

         return CoordsList;


    }

$.fn.annotateImage.ajaxLoad = function (image) {
        ///<summary>
        ///Loads the annotations from the "getUrl" property passed in on the
        ///     options object.
        ///</summary>
      
        $.ajax({
            type: "POST",
            contentType: "application/json; charset=utf-8",
            url: "Default.aspx/GetDynamicContext",
            data: "{'entryId': '" + 1 + "','entryName': '" + 2 + "'}",
            dataType: "json",
            success: function (msg) {
                image.notes = msg.d;
                $.fn.annotateImage.load(image);
            }
        });



 }; 

 $.fn.SaveCoords = function (note) {
        $.ajax({
            type: "POST",
            contentType: "application/json; charset=utf-8",
            url: "Default.aspx/SaveCoords",
            data: "{'top': '" + note.top + "','left': '" + note.left + "','width': '" + note.width + "','height': '" + note.height + "','text': '" + note.text + "','id': '" + note.id + "','editable': '" + note.editable + "'}",
            dataType: "json",
            success: function (msg) {
                note.id = msg.d;
             }
        });



 };




 $.fn.annotateView.prototype.edit = function () {

        ///<summary>

        ///Edits the annotation.

        ///</summary>      

        if (this.image.mode == 'view') {

            this.image.mode = 'edit';

            var annotation = this;

            // Create/prepare the editable note elements

            var editable = new $.fn.annotateEdit(this.image, this.note);

            $.fn.annotateImage.createSaveButton(editable, this.image, annotation);

            // Add the delete button

            var del = $('<a>حذف</a>');

            del.click(function () {

                var form = $('#image-annotate-edit-form form');

                $.fn.annotateImage.appendPosition(form, editable)

                if (annotation.image.useAjax) {

                    $.ajax({

                        type: "POST",

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

                        url: "Default.aspx/DeleteCoords",

                        //                        url: annotation.image.deleteUrl,

                        //                        data: form.serialize(),

                        data: "{'id': '" + editable.note.id + "'}",

                        dataType: "json",

                        success: function (msg) {

                            //                image.notes = msg.d;

                            //                $.fn.annotateImage.load(image);

                        },

                        error: function (e) { alert("An error occured deleting that note.") }

                    });

                }

                annotation.image.mode = 'view';

                editable.destroy();

                annotation.destroy();

            });

            editable.form.append(del);

            $.fn.annotateImage.createCancelButton(editable, this.image);

        }

    };

    <asp:ScriptManager ID="Scriptmanager1" runat="server">
            <Scripts>
                <asp:ScriptReference Name="MicrosoftAjaxWebForms.js" Assembly="System.Web.Extensions"
                    Path="~/staticJS1.js" />
                <asp:ScriptReference Name="MicrosoftAjax.js" Assembly="System.Web.Extensions" Path="~/staticJS2.js" />
            </Scripts>
    </asp:ScriptManager>

 The assembly 'System.Web.Extensions' does not contain a Web resource that has the name 'xyz.js'.
Make sure that the resource name is spelled correctly.
Make sure that the application references the correct version of an ASP.NET AJAX Framework assembly.

 <script src="staticJS1.js" type="text/javascript"></script>
<script src="staticJS2.js" type="text/javascript"></script>