Update 11-middleware.mdx: Added Switcher

docs/02-app/01-building-your-application/01-routing/11-middleware.mdx

@@ -148,7 +148,7 @@ Cookies are regular headers. On a `Request`, they are stored in the `Cookie` hea
 1. For incoming requests, `cookies` comes with the following methods: `get`, `getAll`, `set`, and `delete` cookies. You can check for the existence of a cookie with `has` or remove all cookies with `clear`.
 2. For outgoing responses, `cookies` have the following methods `get`, `getAll`, `set`, and `delete`.
 
-```ts filename="middleware.ts"
+```ts filename="middleware.ts" switcher
 import { NextResponse } from 'next/server'
 import type { NextRequest } from 'next/server'
 
@@ -180,6 +180,37 @@ export function middleware(request: NextRequest) {
 }
 ```
 
+```js filename="middleware.js" switcher
+import { NextResponse } from 'next/server'
+
+export function middleware(request) {
+  // Assume a "Cookie:nextjs=fast" header to be present on the incoming request
+  // Getting cookies from the request using the `RequestCookies` API
+  let cookie = request.cookies.get('nextjs')
+  console.log(cookie) // => { name: 'nextjs', value: 'fast', Path: '/' }
+  const allCookies = request.cookies.getAll()
+  console.log(allCookies) // => [{ name: 'nextjs', value: 'fast' }]
+
+  request.cookies.has('nextjs') // => true
+  request.cookies.delete('nextjs')
+  request.cookies.has('nextjs') // => false
+
+  // Setting cookies on the response using the `ResponseCookies` API
+  const response = NextResponse.next()
+  response.cookies.set('vercel', 'fast')
+  response.cookies.set({
+    name: 'vercel',
+    value: 'fast',
+    path: '/',
+  })
+  cookie = response.cookies.get('vercel')
+  console.log(cookie) // => { name: 'vercel', value: 'fast', Path: '/' }
+  // The outgoing response will have a `Set-Cookie:vercel=fast;path=/test` header.
+
+  return response
+}
+```
+
 ## Setting Headers
 
 You can set request and response headers using the `NextResponse` API (setting _request_ headers is available since Next.js v13.0.0).