richardscarrott/worker.ts

## worker.ts
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));
	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));