Damian's Blog .NET from Geneva, Switzerland

<select id="Countries">
    <option>Switzerland</option>
    <option>United Kindom</option>
    <option>United States</option>
</select>

<script src="/Scripts/MicrosoftAjax.debug.js" type="text/javascript"></script>
<script src="/Scripts/AjaxControlToolkit.Common.Common.js" type="text/javascript"></script>
<script src="/Scripts/AjaxControlToolkit.ExtenderBase.BaseScripts.js" type="text/javascript"></script>
<script src="/Scripts/AjaxControlToolkit.DynamicPopulate.DynamicPopulateBehavior.js" type="text/javascript"></script>
<script src="/Scripts/AjaxControlToolkit.Compat.Timer.Timer.js" type="text/javascript"></script>
<script src="/Scripts/AjaxControlToolkit.Animation.Animations.js" type="text/javascript"></script>
<script src="/Scripts/AjaxControlToolkit.Animation.AnimationBehavior.js" type="text/javascript"></script>
<script src="/Scripts/AjaxControlToolkit.PopupExtender.PopupBehavior.js" type="text/javascript"></script>
<script src="/Scripts/AjaxControlToolkit.PopupControl.PopupControlBehavior.js" type="text/javascript"></script>
<script src="/Scripts/AjaxControlToolkit.ListSearch.ListSearchBehavior.js" type="text/javascript"></script>

<script type="text/javascript">
Sys.Application.initialize();
Sys.Application.add_init(function() {
    $create(AjaxControlToolkit.ListSearchBehavior,
        { "id": "ListBox1_ListSearchExtender" },
        null, null, $get("Countries"));
});
</script>

<select id="Countries">
    <option>Switzerland</option>
    <option>United Kindom</option>
    <option>United States</option>
</select>

<script src="/ControlDependencies/Get?extenderTypeName=AjaxControlToolkit.ListSearchExtender" type="text/javascript"></script>

<script type="text/javascript">
Sys.Application.initialize();
Sys.Application.add_init(function() {
    $create(AjaxControlToolkit.ListSearchBehavior,
        { "id": "ListBox1_ListSearchExtender" },
        null, null, $get("Countries"));
});
</script>

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Web.Mvc;
using AjaxControlToolkit;

namespace TestDependencies.Controllers {
public class ControlDependenciesController : Controller {
    readonly Assembly toolkitAssembly =
        typeof(AjaxControlToolkit.Utility).Assembly;

    [OutputCache(VaryByParam = "extenderTypeName",
                 Duration = 86400,  // One day
                 Location = System.Web.UI.OutputCacheLocation.Client)]
    public ActionResult Get(string extenderTypeName) {

        if (string.IsNullOrEmpty(extenderTypeName)) {
            return new EmptyResult();
        }

        // Get the type representing the extender we are handling
        Type extenderType = toolkitAssembly.GetType(extenderTypeName,
                                                    false);
        if(extenderType == null) {
            return new EmptyResult();
        }

        // What other extenders does this one depend on?
        Stack<Type> dependencies = new Stack<Type>();
        AddDependencies(extenderType, dependencies);

        // What scripts do those extenders require?
        List<string> scriptsToInclude = new List<string>();
        GetDependencyScripts(dependencies, scriptsToInclude);

        return PartialView(scriptsToInclude);
    }

    // Find the types that the specified extender type depends on
    static void AddDependencies(Type extenderType,
                                Stack<Type> dependencies) {
        dependencies.Push(extenderType);
        Attribute[] attributes =
            Attribute.GetCustomAttributes(extenderType,
                      typeof(RequiredScriptAttribute));

        foreach (RequiredScriptAttribute attribute in attributes) {
            AddDependencies(attribute.ExtenderType, dependencies);
        }
    }

    // Find the scripts used by the specified extender types
    static void GetDependencyScripts(IEnumerable<Type> dependencies,
                                     ICollection<string> scripts) {
        foreach (Type dependency in dependencies) {
            Attribute[] attributes =
                Attribute.GetCustomAttributes(dependency,
                           typeof(ClientScriptResourceAttribute));

            foreach (ClientScriptResourceAttribute attribute in attributes) {
                if (!scripts.Contains(attribute.ResourcePath)) {
                    scripts.Add(attribute.ResourcePath);
                }
            }
        }
    }
}
}

using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Web.Mvc;

namespace TestDependencies.Views.ControlDependencies {
  public partial class Get : ViewUserControl<List<string>> {

    protected void Page_Load(object sender, EventArgs e) {
      Response.ContentType = "application/x-javascript";

      // Get compressed stream if possible
      Stream outputStream = GetOutputStream();

      using(StreamWriter outputWriter = new StreamWriter(outputStream)) {

        // Standard AJAX library
        string script = File.ReadAllText(
                              MapPath("/Scripts/MicrosoftAjax.js"));
        outputWriter.WriteLine(script);

        // Required scripts
        foreach(string scriptPath in ViewData.Model) {
          script = File.ReadAllText(MapPath("/Scripts/" + scriptPath));
          outputWriter.WriteLine(script);
        }

      }
      Response.End();
    }

    // Compress scripts if possible -- stolen from ToolkitScriptManager
    // in AJAX Control Toolkit
    private Stream GetOutputStream() {
      Stream outputStream = Response.OutputStream;
      if(!Request.Browser.IsBrowser("IE") ||
                         (6 < Request.Browser.MajorVersion)) {
        foreach(
          string acceptEncoding in (Request.Headers["Accept-Encoding"] ??
                                       "").ToUpperInvariant().Split(',')) {
          if("GZIP" == acceptEncoding) {
            Response.AddHeader("Content-encoding", "gzip");
            outputStream = new GZipStream(outputStream,
                                          CompressionMode.Compress);
            break;
          }
          if("DEFLATE" == acceptEncoding) {
            Response.AddHeader("Content-encoding", "deflate");
            outputStream = new DeflateStream(outputStream,
                                             CompressionMode.Compress);
            break;
          }
        }
      }
      return outputStream;
    }
  }
}

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="Get.ascx.cs" Inherits="TestDependencies.Views.ControlDependencies.Get"  %>