CustomEvent

- LS

A DOM event interface that can carry custom application-defined data.

Chrome

  1. 4: Not supported
  2. 5 - 8: Support unknown
  3. 9 - 12: Partial support
  4. 13 - 14: Support unknown
  5. 15 - 122: Supported
  6. 123: Supported
  7. 124 - 126: Supported

Edge

  1. 12 - 122: Supported
  2. 123: Supported

Safari

  1. 3.1 - 4: Not supported
  2. 5: Support unknown
  3. 5.1: Partial support
  4. 6: Support unknown
  5. 6.1 - 17.3: Supported
  6. 17.4: Supported
  7. TP: Supported

Firefox

  1. 2 - 5: Not supported
  2. 6 - 10: Partial support
  3. 11 - 123: Supported
  4. 124: Supported
  5. 125 - 127: Supported

Opera

  1. 9 - 10.6: Not supported
  2. 11 - 11.5: Partial support
  3. 11.6 - 107: Supported
  4. 108: Supported

IE

  1. 5.5 - 8: Not supported
  2. 9 - 10: Partial support
  3. 11: Partial support

Chrome for Android

  1. 122: Supported

Safari on iOS

  1. 3.2: Support unknown
  2. 4: Not supported
  3. 4.2: Support unknown
  4. 5: Partial support
  5. 6 - 17.3: Supported
  6. 17.4: Supported

Samsung Internet

  1. 4 - 22: Supported
  2. 23: Supported

Opera Mini

  1. all: Supported

Opera Mobile

  1. 10: Not supported
  2. 11 - 11.5: Partial support
  3. 12 - 12.1: Supported
  4. 80: Supported

UC Browser for Android

  1. 15.5: Supported

Android Browser

  1. 2.1 - 2.3: Not supported
  2. 3 - 4.3: Partial support
  3. 4.4 - 4.4.4: Supported
  4. 122: Supported

Firefox for Android

  1. 123: Supported

QQ Browser

  1. 14.9: Supported

Baidu Browser

  1. 13.52: Supported

KaiOS Browser

  1. 2.5: Supported
  2. 3: Supported

Not supported in some versions of Android's old WebKit-based WebView.

Resources:
MDN Web Docs - CustomEvent
EventListener polyfill which includes a CustomEvent polyfill
Polyfill based on the MDN snippet