1. beforeunloadevent api

2. beforeunloadevent api: returnvalue

3. beforeunloadevent api: user interaction required for dialog box

4. notrestoredreasondetails api: reason: unload-listener

5. performancenavigationtiming api: unloadeventend

6. performancenavigationtiming api: unloadeventstart

7. performancetiming api: unloadeventend

8. performancetiming api: unloadeventstart

9. window api: `beforeunload` event

10. window api: `beforeunload` event: activation by setting `event.returnvalue` to any truthy value

11. window api: `beforeunload` event: dialog displays a generic string, not event handler return value

12. window api: `beforeunload` event: activation using `event.preventdefault()`

13. window api: `beforeunload` event: activation by returning a string

14. window api: `unload` event

15. headers http header: permissions-policy: unload