Window Focus Refetching

If a user leaves your application and returns to stale data, React Query automatically requests fresh data for you in the background. You can disable this globally or per-query using the refetchOnWindowFocus option:

Disabling Globally

1 //
2 const queryClient = new QueryClient({
3   defaultOptions: {
4     queries: {
5       refetchOnWindowFocus: false,
6     },
7   },
8 })
9 
10 function App() {
11   return <QueryClientProvider client={queryClient}>...</QueryClientProvider>
12 }

Disabling Per-Query

 useQuery('todos', fetchTodos, { refetchOnWindowFocus: false })

Custom Window Focus Event

In rare circumstances, you may want to manage your own window focus events that trigger React Query to revalidate. To do this, React Query provides a focusManager.setEventListener function that supplies you the callback that should be fired when the window is focused and allows you to set up your own events. When calling focusManager.setEventListener, the previously set handler is removed (which in most cases will be the default handler) and your new handler is used instead. For example, this is the default handler:

1 focusManager.setEventListener(handleFocus => {
2   // Listen to visibilitychange and focus
3   if (typeof window !== 'undefined' && window.addEventListener) {
4     window.addEventListener('visibilitychange', handleFocus, false)
5     window.addEventListener('focus', handleFocus, false)
6   }
7 
8   return () => {
9     // Be sure to unsubscribe if a new handler is set
10     window.removeEventListener('visibilitychange', handleFocus)
11     window.removeEventListener('focus', handleFocus)
12   }
13 })

Ignoring Iframe Focus Events

A great use-case for replacing the focus handler is that of iframe events. Iframes present problems with detecting window focus by both double-firing events and also firing false-positive events when focusing or using iframes within your app. If you experience this, you should use an event handler that ignores these events as much as possible. I recommend this one! It can be set up in the following way:

1 import { focusManager } from 'react-query'
2 import onWindowFocus from './onWindowFocus' // The gist above
3 
4 focusManager.setEventListener(onWindowFocus) // Boom!

Managing Focus in React Native

Instead of event listeners on window, React Native provides focus information through the AppState module. You can use the AppState "change" event to trigger an update when the app state changes to "active":

1 import { AppState } from 'react-native'
2 import { focusManager } from 'react-query'
3 
4 focusManager.setEventListener(handleFocus => {
5   AppState.addEventListener('change', handleFocus)
6 
7   return () => {
8    AppState.removeEventListener('change', handleFocus)
9   }
10 })

Managing focus state

1 import { focusManager } from 'react-query'
2 
3 // Override the default focus state
4 focusManager.setFocused(true)
5 
6 // Fallback to the default focus check
7 focusManager.setFocused(undefined)

Pitfalls & Caveats

Some browser internal dialogue windows, such as spawned by alert() or file upload dialogues (as created by <input type="file" />) might also trigger focus refetching after they close. This can result in unwanted side effects, as the refetching might trigger component unmounts or remounts before your file upload handler is executed. See this issue on GitHub for background and possible workarounds.