What browser feature is this code designed to handle?
window.addEventListener('pageshow', function(event) {
if (event.persisted) {
console.log('This page was restored from the bfcache');
refreshPageContent();
}
});
window.addEventListener('pagehide', function(event) {
if (event.persisted) {
// The page might enter the bfcache
savePageState();
}
});
This code handles the back-forward cache (bfcache): 1) The bfcache is a performance optimization that some browsers use to cache entire pages in memory when navigating away, 2) When a user presses the back button, the cached page can be restored instantly instead of reloading, 3) The pageshow event fires when a page is loaded or restored from the bfcache, 4) The event.persisted property is true when the page is restored from the cache rather than freshly loaded, 5) The pagehide event fires when navigating away from a page, with persisted indicating it might be cached, 6) This code pattern ensures the page refreshes its content when restored from cache (addressing potential stale data), 7) It also saves state before the page might enter the cache, 8) Without this handling, cached pages might display outdated information or break due to expired states.