Incoming "last-modified" requests

• https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Modified-Since
• https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Unmodified-Since

Clients, upon receiving resources with a Last-Modified header, may send requests that contain one or both of the above linked headers. I think handling these headers would be outside the scope of this plugin. At best, I think the incoming request object could be decorated with the values of these headers, e.g.:

fastify.decorateRequest('ifModifiedSince', function () {
  if (!this.req.headers['if-modified-size']) return null
  return new Date(this.req.headers['if-modified-since'])
})

Do you agree @fastify?

[dougwilson]

Express / Koa use the fresh module for this logic, if that helps at all.

[jsumners]

I have opted to ignore the Last-modified mechanism and only support the ETag mechanism. The ETag standard has been around long enough that web browsers should support it. If the desire it to give the clients a hint to not issue a request to the server, then the Expires header can be sent along with the ETag header.