bfcache-ready SvelteKit pages

The browser back/forward cache (bfcache) keeps a full page snapshot in memory so back/forward navigation feels instant. Eligibility depends on the page lifecycle, not SvelteKit itself. These steps keep your routes bfcache-friendly.

Best practices

• Avoid unload and beforeunload listeners; they disable bfcache in most browsers.
• Prefer pagehide/pageshow for cleanup and restore logic.
• When you need to refresh data on return, check event.persisted on pageshow.
• Keep timers and subscriptions idempotent so they can be paused and rehydrated.
• Do not rely on visibilitychange alone; it fires on bfcache restores but is not the canonical signal.
• Avoid forced full reloads on back/forward navigation unless the data must be real-time.

SvelteKit pattern

<svelte:window
	on:pagehide={() => pauseRealtime()}
	on:pageshow={(event) => {
		if (event.persisted) {
			resumeRealtime();
			refreshIfStale();
		}
	}}
/>

Checklist

• No beforeunload or unload listeners on the page.
• pageshow handler checks event.persisted before refetching.
• Subscriptions and intervals can safely resume after a restore.