Window: pagehide event

The pagehide event is sent to a Window when the browser hides the current page in the process of presenting a different page from the session's history. For example, when the user clicks the browser's Back button, the current page receives a pagehide event before the previous page is shown.

Like the unload and beforeunload events, this event is not reliably fired by browsers, especially on mobile. For example, the pagehide event is not fired at all in the following scenario:

1. A mobile user visits your page.
2. The user then switches to a different app.
3. Later, the user closes the browser from the app manager.

However, unlike the unload and beforeunload events, this event is compatible with the back/forward cache (bfcache), so adding a listener to this event will not prevent the page from being included in the bfcache.

The best event to use to signal the end of a user's session is the visibilitychange event. In browsers that don't support visibilitychange the pagehide event is the next-best alternative.

If you're specifically trying to detect page unload events, the pagehide event is the best option.

See the Page Lifecycle API guide for more information about how this event relates to other events in the page lifecycle.

In this example, an event handler is established to watch for pagehide events and to perform special handling if the page is being persisted for possible reuse.

window.addEventListener("pagehide", event => {
  if (event.persisted) {
    /* the page isn't being discarded, so it can be reused later */
  }
}, false);

This can also be written using the onpagehide event handler property on the Window:

window.onpagehide = event => {
  if (event.persisted) {
    /* the page isn't being discarded, so it can be reused later */
  }
}

• The pageshow event.
• Page Lifecycle API gives best-practices guidance on handling page lifecyle behavior in your web applications.
• PageLifecycle.js: a JavaScript library that deals with cross-browser inconsistencies in page lifecyle behavior.
• Back/forward cache explains what the back/forward cache is, and its implications for various page lifecycle events.