Window API: `beforeunload` event: Activation by setting `event.returnValue` to any truthy value
IE
- ❌ 6 - 8: Not supported
- ✅ 9 - 10: Supported
- ✅ 11: Supported
Edge
- ❌ 12 - 18: Not supported
- ◐ 79 - 118: Partial support
- ✅ 119 - 130: Supported
- ✅ 131: Supported
Firefox
- ❌ 2 - 5: Not supported
- ✅ 6 - 132: Supported
- ✅ 133: Supported
- ✅ 134 - 136: Supported
Chrome
- ❌ 4 - 29: Not supported
- ◐ 30 - 118: Partial support
- ✅ 119 - 130: Supported
- ✅ 131: Supported
- ✅ 132 - 134: Supported
Safari
- ❌ 3.1 - 7.1: Not supported
- ✅ 8 - 18.0: Supported
- ✅ 18.1: Supported
- ✅ 18.2 - TP: Supported
Opera
- ❌ 10 - 16: Not supported
- ◐ 17 - 104: Partial support
- ✅ 105 - 113: Supported
- ✅ 114: Supported
Safari on iOS
- ❌ 3.2 - 18.0: Not supported
- ❌ 18.1: Not supported
- ❌ 18.2: Not supported
Opera Mini
- ﹖ all: Support unknown
Android Browser
- ❌ 2.1 - 4.3: Not supported
- ◐ 4.4 - 4.4.4: Partial support
- ✅ 131: Supported
Opera Mobile
- ❌ 12 - 12.1: Not supported
- ✅ 80: Supported
Chrome for Android
- ✅ 131: Supported
Firefox for Android
- ✅ 132: Supported
UC Browser for Android
- ﹖ 15.5: Support unknown
Samsung Internet
- ◐ 4 - 24: Partial support
- ✅ 25: Supported
- ✅ 26: Supported
QQ Browser
- ﹖ 14.9: Support unknown
Baidu Browser
- ﹖ 13.52: Support unknown
KaiOS Browser
- ﹖ 2.5: Support unknown
- ﹖ 3: Support unknown