setupListeners

A utility used to enable refetchOnFocus and refetchOnReconnect behaviors. It requires the dispatch method from your store. Calling setupListeners(store.dispatch) will configure listeners with the recommended defaults, but you have the option of providing a callback for more granular control.

setupListeners default configuration

let initialized = false
export function setupListeners(
  dispatch: ThunkDispatch<any, any, any>,
  customHandler?: (
    dispatch: ThunkDispatch<any, any, any>,
    actions: {
      onFocus: typeof onFocus
      onFocusLost: typeof onFocusLost
      onOnline: typeof onOnline
      onOffline: typeof onOffline
    },
  ) => () => void,
) {
  function defaultHandler() {
    const handleFocus = () => dispatch(onFocus())
    const handleFocusLost = () => dispatch(onFocusLost())
    const handleOnline = () => dispatch(onOnline())
    const handleOffline = () => dispatch(onOffline())
    const handleVisibilityChange = () => {
      if (window.document.visibilityState === 'visible') {
        handleFocus()
      } else {
        handleFocusLost()
      }
    }

    if (!initialized) {
      if (typeof window !== 'undefined' && window.addEventListener) {
        // Handle focus events
        window.addEventListener(
          'visibilitychange',
          handleVisibilityChange,
          false,
        )
        window.addEventListener('focus', handleFocus, false)

        // Handle connection events
        window.addEventListener('online', handleOnline, false)
        window.addEventListener('offline', handleOffline, false)
        initialized = true
      }
    }
    const unsubscribe = () => {
      window.removeEventListener('focus', handleFocus)
      window.removeEventListener('visibilitychange', handleVisibilityChange)
      window.removeEventListener('online', handleOnline)
      window.removeEventListener('offline', handleOffline)
      initialized = false
    }
    return unsubscribe
  }

  return customHandler
    ? customHandler(dispatch, { onFocus, onFocusLost, onOffline, onOnline })
    : defaultHandler()
}

If you notice, onFocus, onFocusLost, onOffline, onOnline are all actions that are provided to the callback. Additionally, these actions are made available to api.internalActions and are able to be used by dispatching them like this:

Manual onFocus event

dispatch(api.internalActions.onFocus())