Add middleware to include charset in HTTP header for early detection

Author: webstackdev

src/middleware.ts

@@ -0,0 +1,19 @@
+import { defineMiddleware } from 'astro:middleware'
+
+export const onRequest = defineMiddleware(async (_context, next) => {
+  const response = await next()
+  const contentType = response.headers.get('content-type')
+
+  if (!contentType || !contentType.startsWith('text/html') || /charset=/i.test(contentType)) {
+    return response
+  }
+
+  const headers = new Headers(response.headers)
+  headers.set('content-type', `${contentType}; charset=utf-8`)
+
+  return new Response(response.body, {
+    status: response.status,
+    statusText: response.statusText,
+    headers,
+  })
+})