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Cloudflare Workers / Pages `stale-while-revalidate`
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| import { parse } from 'cache-control-parser'; | |
| export default { | |
| async fetch(request: Request, env: {}, ctx: ExecutionContext): Promise<Response> { | |
| try { | |
| const cache = await caches.default; | |
| const cachedResponse = await cache.match(request); | |
| if (cachedResponse) { | |
| console.log('Cache: HIT'); | |
| if (shouldRevalidate(cachedResponse)) { | |
| console.log('Cache: REVALIDATE'); | |
| ctx.waitUntil(handleRequest(request, env, ctx).then((response) => cache.put(request, response.clone()))); | |
| } | |
| return cachedResponse; | |
| } | |
| console.log('Cache: MISS'); | |
| const response = await handleRequest(request, env, ctx); | |
| ctx.waitUntil(cache.put(request, response.clone())); | |
| return response; | |
| } catch (ex) { | |
| console.error(ex); | |
| return new Response('Internal server error', { status: 500 }); | |
| } | |
| }, | |
| }; | |
| // e.g. Remix handler | |
| const handleRequest = async (request: Request, env: {}, ctx: ExecutionContext): Promise<Response> => { | |
| const response = await fetch('https://swapi.dev/api/people/1/'); | |
| if (!response.ok) { | |
| return new Response(JSON.stringify({ error: `${response.status}: ${response.statusText}` }), { status: 500 }); | |
| } | |
| const result = await response.json(); | |
| await sleep(2000); | |
| return new Response( | |
| ` | |
| <!doctype html> | |
| <html> | |
| <head> | |
| <title>Hello world</title> | |
| </head> | |
| <body> | |
| <h1>Success</h1> | |
| <div>0.0.2</div> | |
| <div>${new Date().toString()}</div> | |
| <pre>${JSON.stringify(result, null, 2)}</pre> | |
| </body> | |
| </html> | |
| `, | |
| { | |
| headers: { | |
| 'content-type': 'text/html', | |
| 'cache-control': 'no-cache, no-store, must-revalidate', | |
| 'cdn-cache-control': 'max-age=14400, stale-while-revalidate=10', | |
| }, | |
| } | |
| ); | |
| }; | |
| const shouldRevalidate = (cachedResponse: Response) => { | |
| const ageHeader = cachedResponse.headers.get('age'); | |
| const cacheControlHeader = cachedResponse.headers.get('cdn-cache-control'); | |
| if (!ageHeader || !cacheControlHeader) { | |
| return false; | |
| } | |
| const staleWhileRevalidate = parse(cacheControlHeader)['stale-while-revalidate']; | |
| if (typeof staleWhileRevalidate === 'undefined') { | |
| return false; | |
| } | |
| const age = Number(ageHeader); | |
| if (Number.isNaN(age)) { | |
| return false; | |
| } | |
| return age > staleWhileRevalidate; | |
| }; | |
| const sleep = (duration: number) => new Promise((resolve) => setTimeout(resolve, duration)); |
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Very neat, works like a charm! Can we also use a regular header without the
CDN-prefix for browser cache or should we not? Thx.I've seen another implementation before, might that be better for some edge cases (seems overengineered)?