Pagehide Event

What the pagehide event does

The pagehide event marks a transition out of the current page view. Unlike unload, it is designed to work with modern browser lifecycle behaviour, including back-forward cache handling, so scripts can respond when the page is being hidden rather than assuming the document is permanently gone.

That distinction matters because a hidden page may be resumed later. Code that treats page exit as final can break state restoration, duplicate work, or lose pending changes when the browser preserves the page for a later return.

Where pagehide fits in the browser lifecycle

pagehide sits in the browser's page lifecycle, where a document may be suspended, cached, or replaced by another page. It is therefore a coordination point for cleanup logic that needs to run when visibility is ending, but before the browser fully discards the page context.

This makes it useful for logic that depends on lifecycle state rather than navigation intent. A page can be hidden because the user navigates away, switches tabs, or enters a history state that the browser may preserve for fast restoration.

Why pagehide is preferred over unload

Modern browsers increasingly restrict or ignore fragile exit-time behaviour, especially when pages participate in back-forward cache. The pagehide event is better aligned with that model because it lets developers observe the lifecycle transition without relying on a terminal unload path that browsers may skip or treat inconsistently.

For application code, that means cleaner separation between transient in-memory state and persisted state. It also reduces dependence on synchronous shutdown logic that can be slow, unreliable, or incompatible with browser caching optimisations.

Common implementation patterns

Typical uses include saving draft form data, pausing timers, releasing temporary UI state, flushing analytics or session metadata, and marking a page as no longer active. The right behaviour depends on whether the page is merely hidden, cached for later reuse, or truly leaving the session.

• Persist user state before it becomes unavailable.
• Avoid assuming the page will not return.
• Keep lifecycle handlers lightweight so they do not interfere with cache eligibility.
• Separate cleanup that is safe on hide from cleanup that should happen only on permanent teardown.

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