BeforeUnloadEvent
The BeforeUnloadEvent
interface represents the event object for the beforeunload
event, which is fired when the current window, contained document, and associated resources are about to be unloaded.
See the beforeunload
event reference for detailed guidance on using this event.
Instance properties
Inherits properties from its parent, Event
.
returnValue
Deprecated-
When set to a truthy value, triggers a browser-controlled confirmation dialog asking users to confirm if they want to leave the page when they try to close or reload it. This is a legacy feature, and best practice is to trigger the dialog by invoking
event.preventDefault()
, while also settingreturnValue
to support legacy cases.
Instance methods
Inherits methods from its parent, Event
.
Specifications
Specification |
---|
HTML Standard # the-beforeunloadevent-interface |
Browser compatibility
BCD tables only load in the browser
See also
beforeunload
event