Remove source map references from compiled assets

CHANGELOG.md

@@ -10,6 +10,12 @@ The `asp-for` attribute is now obsolete; the `for` attribute should be used in i
 #### `<govuk-error-message>` and `<govuk-fieldset>` tag helpers
 The `<govuk-error-message>` and `<govuk-fieldset>` tag helpers are deprecated and will be removed in a future release.
 
+### Fixes
+
+#### Source map errors
+The hosted CSS and JavaScript files no longer have source maps.
+Any console errors from browsers failing to download the referenced files should be eliminated.
+
 ## 2.8.0
 
 Targets GOV.UK Frontend v5.8.0.

src/GovUk.Frontend.AspNetCore/GovUkFrontendAspNetCoreStartupFilter.cs

@@ -29,7 +29,7 @@ public Action<IApplicationBuilder> Configure(Action<IApplicationBuilder> next)
                     typeof(GovUkFrontendAspNetCoreStartupFilter).Assembly,
                     root: "Content/Compiled");
 
-                app.UseMiddleware<RewriteCssUrlsMiddleware>(fileProvider);
+                app.UseMiddleware<RewriteCompiledAssetsMiddleware>(fileProvider);
 
                 app.UseStaticFiles(new StaticFileOptions()
                 {

src/GovUk.Frontend.AspNetCore/RewriteCompiledAssetsMiddleware.cs

@@ -0,0 +1,68 @@
+using System;
+using System.IO;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.FileProviders;
+using Microsoft.Extensions.Options;
+
+namespace GovUk.Frontend.AspNetCore;
+
+internal class RewriteCompiledAssetsMiddleware
+{
+    private readonly RequestDelegate _next;
+    private readonly IFileProvider _fileProvider;
+    private readonly IOptions<GovUkFrontendAspNetCoreOptions> _optionsAccessor;
+
+    public RewriteCompiledAssetsMiddleware(
+        RequestDelegate next,
+        IFileProvider fileProvider,
+        IOptions<GovUkFrontendAspNetCoreOptions> optionsAccessor)
+    {
+        ArgumentNullException.ThrowIfNull(next);
+        ArgumentNullException.ThrowIfNull(fileProvider);
+        ArgumentNullException.ThrowIfNull(optionsAccessor);
+        _next = next;
+        _fileProvider = fileProvider;
+        _optionsAccessor = optionsAccessor;
+    }
+
+    public async Task InvokeAsync(HttpContext context)
+    {
+        if (_optionsAccessor.Value.CompiledContentPath is PathString compiledContentPath &&
+            _optionsAccessor.Value.StaticAssetsContentPath is PathString staticAssetsPath)
+        {
+            if (context.Request.Path == compiledContentPath + "/all.min.css")
+            {
+                var fileInfo = _fileProvider.GetFileInfo("all.min.css");
+
+                using var readStream = fileInfo.CreateReadStream();
+                using var streamReader = new StreamReader(readStream);
+                var css = await streamReader.ReadToEndAsync();
+
+                css = css.Replace("url(/assets/", $"url({context.Request.PathBase}{staticAssetsPath}/");
+                css = css.Replace("/*# sourceMappingURL=govuk-frontend.min.css.map */", "");
+
+                context.Response.Headers.ContentType = new Microsoft.Extensions.Primitives.StringValues("text/css");
+                await context.Response.WriteAsync(css);
+                return;
+            }
+
+            if (context.Request.Path == compiledContentPath + "/all.min.js")
+            {
+                var fileInfo = _fileProvider.GetFileInfo("all.min.js");
+
+                using var readStream = fileInfo.CreateReadStream();
+                using var streamReader = new StreamReader(readStream);
+                var css = await streamReader.ReadToEndAsync();
+
+                css = css.Replace("//# sourceMappingURL=govuk-frontend.min.js.map", "");
+
+                context.Response.Headers.ContentType = new Microsoft.Extensions.Primitives.StringValues("text/javascript");
+                await context.Response.WriteAsync(css);
+                return;
+            }
+        }
+
+        await _next(context);
+    }
+}