Can I use
?

Window API: `beforeunload` event: Activation by setting `event.returnValue` to any truthy value

IE

  1. ❌ 6 - 8: Not supported
  2. ✅ 9 - 10: Supported
  3. ✅ 11: Supported

Edge

  1. ❌ 12 - 18: Not supported
  2. ◐ 79 - 118: Partial support
  3. ✅ 119 - 154: Supported
  4. ✅ 155: Supported

Firefox

  1. ❌ 2 - 5: Not supported
  2. ✅ 6 - 158: Supported
  3. ✅ 159: Supported
  4. ✅ 160 - 162: Supported

Chrome

  1. ❌ 4 - 29: Not supported
  2. ◐ 30 - 118: Partial support
  3. ✅ 119 - 155: Supported
  4. ✅ 156: Supported
  5. ✅ 157 - 159: Supported

Safari

  1. ❌ 3.1 - 7.1: Not supported
  2. ✅ 8 - 26.6: Supported
  3. ✅ 27: Supported
  4. ✅ 27.1 - TP: Supported

Opera

  1. ❌ 10 - 16: Not supported
  2. ◐ 17 - 104: Partial support
  3. ✅ 105 - 134: Supported
  4. ✅ 135: Supported

Safari on iOS

  1. ❌ 3.2 - 26.6: Not supported
  2. ❌ 27.0: Not supported
  3. ❌ 27.1 - 27.2: Not supported

Opera Mini

  1. ﹖ all: Support unknown

Android Browser

  1. ❌ 2.1 - 4.3: Not supported
  2. ◐ 4.4 - 4.4.4: Partial support
  3. ✅ 156: Supported

Opera Mobile

  1. ❌ 12 - 12.1: Not supported
  2. ✅ 80: Supported

Chrome for Android

  1. ✅ 156: Supported

Firefox for Android

  1. ✅ 159: Supported

UC Browser for Android

  1. ◐ 15.5: Partial support

Samsung Internet

  1. ◐ 4 - 24: Partial support
  2. ✅ 25 - 29: Supported
  3. ✅ 30: Supported

QQ Browser

  1. ◐ 14.9: Partial support

Baidu Browser

  1. ﹖ 13.52: Support unknown

KaiOS Browser

  1. ◐ 2.5: Partial support
  2. ◐ 3: Partial support