Learn Performance - Caching

This demo utilizes the Last-Modified response header to validate the freshness of the server response. Similarly to the ETag, the first time you visit this page, the browser receives the full response from the server. The response includes the last-modified header containing the date when the response was generated. This should match the timestamp shown above.

The browser will store the received last-modified date and include it on every subsequent request using the if-modified-since header. If the data is older than the if-modified-since value, then the server will respond with a 304 status code and the browser can reuse the cached data.

if (time <= request.headers["if-modified-since"]) {
  reply.statusCode = 304;
  reply.send();
} else {
  reply.headers({
    "cache-control": "no-cache",
    "last-modified": time,
  });
  reply.view("/src/pages/3.hbs", params);
}

return reply;