A window’s onbeforeunload property may be set to a function that returns a string. If the function returns a string, then before unloading the page, a dialog is shown to have the user confirm that they indeed want to navigate away. The string provided by the function will no longer be shown in the dialog. Rather, a generic string not under the control of the webpage will be shown.
Specification
Final published standard: Recommendation, Living Standard, Candidate Recommendation, or similar final form
Status in Chromium
Removed
(tracking bug)
Consensus & Standardization
After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.
- Shipped/Shipping
- Shipped/Shipping
- Negative
Owner
Last updated on 2020-11-09
Comments
This shipped in Safari 9.1, and has been shipping in Firefox since Firefox 4. Safari considers this a security fix and assigned it CVE-2009-2197 (see https://support.apple.com/en-us/HT206171 ). Approved with the intent https://groups.google.com/a/chromium.org/d/msg/blink-dev/YIH8CoYVGSg/Di7TsljXDQAJ .