Create a new ASP.NET Web Application project using the Empty template by following the steps listed in the Adding jQuery to an empty ASP.NET web project using a script block recipe. Name the project WebApplication2 (or any other suitable name).

Follow the steps in the preceding recipe to add the jQuery library (the uncompressed and compressed formats) to the Scripts folder.

Follow the steps to add a new web form to the project.

Open the web form in the Design mode.

Launch the Toolbox. This can be done in two ways. From the File menu at the top of the page, go to View | Toolbox. Alternatively, use the shortcut keys, Ctrl + Alt + X.

Go to Toolbox | AJAX Extensions, and drag and drop the ScriptManager control onto the form:

Right-click on the project in the Solution Explorer tab, and go to Add | New Item.... From the dialog box, select Global Application Class. This will add the Global.asax file to the project:

Open the Global.asax file and include the following namespace at the top of the page:

For VB, the code is as follows:

Imports System.Web.UI

For C#, the code is as follows:

using System.Web.UI;

In the Application_Start event in the Global.asax file, add the following code to create a script that maps to jQuery:

For VB, the code is as follows:

Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)
   ScriptManager.ScriptResourceMapping.AddDefinition("jquery", New ScriptResourceDefinition() With {
   .Path = "~/Scripts/jquery-2.1.4.min.js",
   .DebugPath = "~/Scripts/jquery-2.1.4.js",
   .CdnPath = "https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js",
   .CdnDebugPath = "https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.js",
   .CdnSupportsSecureConnection = True,
   .LoadSuccessExpression = "window.jQuery"})
End Sub

For C#, the code is as follows:

protected void Application_Start(object sender, EventArgs e)
{            
   ScriptManager.ScriptResourceMapping.AddDefinition("jquery", new     ScriptResourceDefinition
   {
      Path = "~/Scripts/jquery-2.1.4.min.js",
      DebugPath = "~/Scripts/jquery-2.1.4.js",
      CdnPath = "https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js",
      CdnDebugPath = "https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.js",
      CdnSupportsSecureConnection = true,
      LoadSuccessExpression = "window.jQuery"
    });
}

Open the Default.aspx web form in the Source mode. Add the following ScriptReference to the ScriptManager control:

<asp:ScriptManager ID="ScriptManager1" runat="server">
     <Scripts>
          <asp:ScriptReference Name="jquery"  />
     </Scripts>
</asp:ScriptManager>

To retrieve the jQuery files from CDN, set the EnableCdn property of the ScriptManager control to true, as follows:

<asp:ScriptManager ID="ScriptManager1" runat="server" EnableCdn="true">
     <Scripts>
          <asp:ScriptReference Name="jquery"  />
     </Scripts>
</asp:ScriptManager>

The ScriptManager control can be used to load JavaScript files, such as the jQuery library. This can be done by adding the ScriptReference to jQuery in the ScriptManager control, as follows:

<asp:ScriptReference Name="jquery"  />

However, we require to define this mapping. This can be done in the Global.asax file using a ScriptResourceDefinition object, which exposes the following properties:

The ScriptResourceDefinition object defined in Global.asax is named jquery. The ScriptManager control uses the same name to load the reference on the web form.

In the development/debug mode, the script is served from DebugPath while in the release mode, it is served from Path.

<system.web>
    <compilation debug="true"/>
    …..
</system.web>  

If EnableCdn is set to true, the script is served from the CDN path, that is, from CdnDebugPath in the development/debug mode and CdnPath in the release mode.

The LoadSuccessExpression property renders an inline script to load the library from the local path in the event of a CDN failure. By right-clicking on the web page and viewing the source, note that the ScriptManager control adds a fall back mechanism when the CDN is unavailable and files are served locally instead: