Re-check on return

When someone comes back to your app after a while (the tab is visible again, the window regains focus, or React Native's AppState becomes active), the last probe may be old. useRecheckOnReturn re-probes at once instead of waiting for the next scheduled check.

It is opt-in per screen. By default the detector does not even subscribe to the foreground signal, so a screen that does not care pays nothing.

import { useRecheckOnReturn } from '@rogeriodocarmo/offline-detector-web'; // or '-native'

function Checkout() {
  const online = useRecheckOnReturn({
    checkingFeedback: 'brief',
    onResult: (isOnline) => console.log('back in the app, online:', isOnline),
  });
  return <Pay disabled={!online} />;
}

Options

Option	Default	Notes
checkingFeedback	'none'	'brief' or 'none'. Whether the return check is visible.
onResult	none	(isOnline: boolean) => void, called after each return-triggered check

The hook returns the latest known boolean: false only when the app is offline. It updates with every state change, not only after a return.

'brief' versus 'none'

Source of the check	'none'	'brief'
Re-probe on return to the app	nothing visible	the pieces show a short "Checking…" state
The user presses Retry	the button shows "Checking…"	same (a pressed Retry always shows it)
A scheduled back-off probe while offline	nothing visible	nothing visible (only return-triggered checks)
Online, nothing wrong	nothing visible	nothing visible: a successful brief check shows nothing

Rules for 'brief':

• The "Checking…" state shows only if the check is still pending after 150 ms, and once shown it stays for at least 400 ms. That avoids a flash on a fast network and flicker on a slow one.
• It never moves layout: a spinner replaces the label inside the same box.

Details worth knowing

• The hook subscribes with the adapter only while the component is mounted and unsubscribes on unmount. onResult is not called after unmount.
• Several mounted hooks share one probe, because the core de-duplicates concurrent checks.
• The core's own recheckOnForeground option stays off. This hook is the only place that re-checks on return.
• useCheckingFeedback() is for UI packages: it reports 'brief' while a return check started by a 'brief' hook is pending, and 'none' otherwise.

See the react reference for the exact types.