Web features explorer

Beforeunload

Limited availability
Tags: api

The beforeunload event is fired when the current window is about to be unloaded. Typically this is used to display a dialog to confirm if users really want to leave the page when there is unsaved data that would be lost. To learn more, see Window: beforeunload event at MDN.

Compatibility

Baseline availability blocked since November 2023 by Safari on iOS (12 months)