fix: pass in new headers

Author: taty2010

demos/middleware/middleware.ts

@@ -40,7 +40,8 @@ export async function middleware(req: NextRequest) {
     // request.rewrite() should return the MiddlewareResponse obj instead of the Response obj
     const res = await request.rewrite('/static-rewrite', {
       headers: {
-        'x-rewrite-test': 'hello'
+        'x-rewrite-test': 'hello',
+        'x-rewrite-test-2': 'hello-2'
       }
     })
     const message = `This was static (& escaping test &) but has been transformed in ${req.geo?.city}`
@@ -52,6 +53,7 @@ export async function middleware(req: NextRequest) {
 
     res.headers.set('x-modified-edge', 'true')
     res.headers.set('x-is-deno', 'Deno' in globalThis ? 'true' : 'false')
+    console.log({res})
     return res
   }
 

packages/next/src/middleware/response.ts

@@ -10,7 +10,7 @@ export type NextDataTransform = <T extends { pageProps?: Record<string, any> }>(
 export class MiddlewareResponse extends NextResponse {
   private readonly dataTransforms: NextDataTransform[]
   private readonly elementHandlers: Array<[selector: string, handlers: ElementHandlers]>
-  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+
   constructor(public originResponse: Response, init?: ResponseInit) {
     // we need to propagate the set-cookie header, so response.cookies.get works correctly
     const initHeaders = new Headers()
@@ -22,6 +22,12 @@ export class MiddlewareResponse extends NextResponse {
       headers: initHeaders,
     })
 
+    if (init?.headers) {
+      Object.entries(init.headers).forEach(([key, value]) => {
+        this.headers.set(key, value)
+      })
+    }
+
     // These are private in Node when compiling, but we access them in Deno at runtime
     Object.defineProperty(this, 'dataTransforms', {
       value: [],