Prevent background update for data when network is offline.

[bonatdev]

I am using PWA with CRA,
so is it possible if the network was offline to prevent replacing old data with the new on, in this case, error, because the network is offline?

[pke]

I think you can easily implement that with a check in you fetch function.

function networkAwareFetch(staleData, ...args) {
  return isOnline()
    .then(() => fetch(...args))
    .catch(() => staleData)
}

[sergiodxa]

Instead of passing staleData to the fetcher you could get it from the cache with

import { cache } from "swr"
function networkAwareFetch(...key) {
  return isOnline()
    .then(() => fetch(...args))
    .catch(() => cache.get(key))
}

[pke]

Cool. I didn't know about the cache. Is this a new export?
Also the fetcher is now bound to swr, while my solution could be plugged into any framework. Also your function signature seems to be off, where is ...args coming from now?

[sergiodxa]

Cache has been exported for a while, but it's still not documented, has been pretty stable tho.

About the ...args is because I copied it from your example and forgot to edit it, that should be ...key.

And yes, it will bound it to SWR.

[JaneJeon]

I myself create a middleware that returns stale data and empty error if we detect a network error.