added noCors middleware

CHANGELOG.md

@@ -8,6 +8,7 @@ Go to the `v1` branch to see the changelog of Lume 1.
 ## [2.2.1] - Unreleased
 ### Added
 - Allow to run a server with `deno serve -A _config.ts`.
+- New `noCors` middleware to prevent CORS errors during development.
 
 ### Fixed
 - Port detection in `lume cms` command.

cli/build.ts

@@ -5,6 +5,7 @@ import Server from "../core/server.ts";
 import { SiteWatcher } from "../core/watcher.ts";
 import logger from "../middlewares/logger.ts";
 import noCache from "../middlewares/no_cache.ts";
+import noCors from "../middlewares/no_cors.ts";
 import notFound from "../middlewares/not_found.ts";
 import reload from "../middlewares/reload.ts";
 import { createSite } from "./run.ts";
@@ -112,6 +113,7 @@ export async function build(
   server.use(
     reload({ watcher: new SiteWatcher(site) }),
     noCache(),
+    noCors(),
     notFound({
       root,
       page404,

middlewares/no_cors.ts

@@ -0,0 +1,11 @@
+import type { Middleware } from "../core/server.ts";
+
+/** Add a header to prevent CORS errors (used in development) */
+export default function noCors(): Middleware {
+  return async (request, next) => {
+    const response = await next(request);
+    response.headers.set("access-control-allow-origin", "*");
+
+    return response;
+  };
+}