Form validation

- LS

Method of setting required fields and field types without requiring JavaScript. This includes preventing forms from being submitted when appropriate, the checkValidity() method as well as support for the :invalid, :valid, and :required CSS pseudo-classes.

IE

  1. 5.5 - 9: Not supported
  2. 10: Supported
  3. 11: Supported

Edge

  1. 12 - 102: Supported
  2. 103: Supported

Firefox

  1. 2 - 3.6: Not supported
  2. 4 - 101: Supported
  3. 102: Supported
  4. 103 - 104: Supported

Chrome

  1. 4 - 9: Not supported
  2. 10 - 102: Supported
  3. 103: Supported
  4. 104 - 106: Supported

Safari

  1. 3.1 - 4: Not supported
  2. 5 - 10: Partial support
  3. 10.1 - 15.4: Supported
  4. 15.5: Supported
  5. 16.0 - TP: Supported

Opera

  1. 9 - 9.6: Not supported
  2. 10 - 85: Supported
  3. 86: Supported
  4. 87: Supported

Safari on iOS

  1. 3.2: Not supported
  2. 4 - 10.2: Partial support
  3. 10.3 - 15.4: Supported
  4. 15.5: Supported
  5. 16.0: Supported

Opera Mini

  1. all: Partial support

Android Browser

  1. 2.1 - 3: Not supported
  2. 4 - 4.4: Partial support
  3. 4.4.3: Supported
  4. 103: Supported

Opera Mobile

  1. 10 - 12.1: Supported
  2. 64: Supported

Chrome for Android

  1. 103: Supported

Firefox for Android

  1. 101: Supported

UC Browser for Android

  1. 12.12: Supported

Samsung Internet

  1. 4 - 16.0: Supported
  2. 17.0: Supported

QQ Browser

  1. 10.4: Supported

Baidu Browser

  1. 7.12: Supported

KaiOS Browser

  1. 2.5: Partial support
Resources:
WebKit Blog: HTML Interactive Form Validation
WebPlatform Docs
Sub-features:
Pattern attribute for input fields
Minimum length attribute for input fields
maxlength attribute for input and textarea elements
:optional CSS pseudo-class