Make RESX files available at client-side for JavaScript.

Resources.aspx.cs

using System;
using System.Web.UI;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Reflection;
using System.Resources;

namespace AspNetWebFormsApp
{
    /// <summary>
    /// This page generates a JavaScript file from a certain resource file within the App_GlobalResources folder.
    /// The keys are available from JavaScript with the window.Resources global variable.
    /// </summary>
    public partial class Resources : Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            // TODO: Set your resource class key here.
            const string classKey = "MyResourceFileClassKey";
            WriteAsJson(GetResources(classKey));
        }

        private static IEnumerable<DictionaryEntry> GetResources(string classKey)
        {
            string baseName = $"Resources.{classKey}";
            var resourceManager = new ResourceManager(baseName, Assembly.Load("App_GlobalResources"));
            ResourceSet resourceSet = resourceManager.GetResourceSet(CultureInfo.CurrentUICulture, true, true);
            return resourceSet.Cast<DictionaryEntry>();
        }

        private void WriteAsJson(IEnumerable<DictionaryEntry> resourceSet)
        {
            Response.Clear();
            Response.ContentType = "text/javascript; charset=utf-8";
            Response.Write("window.Resources = {\n");
            foreach (DictionaryEntry entry in resourceSet)
            {
                string key = Escape((string) entry.Key);
                string value = Escape((string) entry.Value);
                Response.Write($"'{key}': '{value}',\n");
            }
            Response.Write("}");
            Response.End();
        }

        private string Escape(string s)
        {
            return s.Replace("'", @"\'").Replace("\r", "").Replace("\n", @"\n");
        }
    }
}