Can I use
?

Custom Elements (deprecated V0 spec)

- UNOFF

Original V0 version of the custom elements specification. See Custom Elements V1 for support for the latest version.

Chrome

  1. 4 - 26: Not supported
  2. 27 - 32: Disabled by default
  3. 33 - 79: Supported
  4. 80 - 106: Not supported
  5. 107: Not supported
  6. 108 - 110: Not supported

Edge

  1. 12 - 18: Not supported (but has polyfill available)
  2. 79: Supported
  3. 80 - 106: Not supported
  4. 107: Not supported

Safari

  1. 3.1 - 5.1: Not supported
  2. 6 - 16.0: Not supported (but has polyfill available)
  3. 16.1: Not supported (but has polyfill available)
  4. 16.2 - TP: Not supported (but has polyfill available)

Firefox

  1. 2 - 22: Not supported
  2. 23 - 29: Disabled by default
  3. 30 - 58: Disabled by default
  4. 59 - 106: Not supported
  5. 107: Not supported
  6. 108 - 109: Not supported

Opera

  1. 9 - 12.1: Not supported
  2. 15 - 19: Disabled by default
  3. 20 - 66: Supported
  4. 67 - 91: Not supported
  5. 92: Not supported

IE

  1. 5.5 - 9: Not supported
  2. 10: Not supported (but has polyfill available)
  3. 11: Not supported (but has polyfill available)

Chrome for Android

  1. 107: Not supported

Safari on iOS

  1. 3.2 - 6.1: Not supported
  2. 7 - 16.0: Not supported (but has polyfill available)
  3. 16.1: Not supported (but has polyfill available)

Samsung Internet

  1. 4 - 12.0: Supported
  2. 13.0 - 18.0: Not supported
  3. 19.0: Not supported

Opera Mini

  1. all: Not supported

Opera Mobile

  1. 10 - 12.1: Not supported
  2. 72: Not supported

UC Browser for Android

  1. 13.4: Supported

Android Browser

  1. 2.1 - 4.4: Not supported
  2. 4.4.3: Supported
  3. 107: Not supported

Firefox for Android

  1. 106: Not supported

QQ Browser

  1. 13.1: Supported

Baidu Browser

  1. 13.18: Not supported

KaiOS Browser

  1. 2.5: Disabled by default
Resources:
Blog post on upgrading from V0 to V1