es-fresh

This is a copy of @foxify/fresh package but with ESM and CommonJS targets.

HTTP response freshness testing.

Install

1pnpm i es-fresh

API

1import fresh from 'es-fresh'

fresh(reqHeaders, resHeaders)

Check freshness of the response using request and response headers.

When the response is still "fresh" in the client's cache true is returned, otherwise false is returned to indicate that the client cache is now stale and the full response should be sent.

When a client sends the Cache-Control: no-cache request header to indicate an end-to-end reload request, this module will return false to make handling these requests transparent.

Example

1import fresh from 'es-fresh'
2import { createServer } from 'http'
3
4function isFresh(req, res) {
5  return fresh(req.headers, {
6    etag: res.getHeader('ETag'),
7    'last-modified': res.getHeader('Last-Modified'),
8  })
9}
10
11createServer((req, res) => {
12  // perform server logic
13  // ... including adding ETag / Last-Modified response headers
14
15  if (isFresh(req, res)) {
16    // client has a fresh copy of resource
17    res.statusCode = 304
18    res.end()
19    return
20  }
21
22  // send the resource
23  res.statusCode = 200
24  res.end('hello, world!')
25}).listen(3000)

License

MIT © v1rtl