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.

Chrome

  1. 4 - 9: Not supported
  2. 10 - 123: Supported
  3. 124: Supported
  4. 125 - 127: Supported

Edge

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

Safari

  1. 3.1 - 4: Not supported
  2. 5 - 10: Partial support
  3. 10.1 - 17.3: Supported
  4. 17.4: Supported
  5. 17.5 - TP: Supported

Firefox

  1. 2 - 3.6: Not supported
  2. 4 - 124: Supported
  3. 125: Supported
  4. 126 - 128: Supported

Opera

  1. 9 - 9.6: Not supported
  2. 10 - 108: Supported
  3. 109: Supported

IE

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

Chrome for Android

  1. 123: Supported

Safari on iOS

  1. 3.2: Not supported
  2. 4 - 10.2: Partial support
  3. 10.3 - 17.3: Supported
  4. 17.4: Supported
  5. 17.5: Supported

Samsung Internet

  1. 4 - 23: Supported
  2. 24: Supported

Opera Mini

  1. all: Partial support

Opera Mobile

  1. 10 - 12.1: Supported
  2. 80: Supported

UC Browser for Android

  1. 15.5: Supported

Android Browser

  1. 2.1 - 3: Not supported
  2. 4 - 4.4: Partial support
  3. 4.4.3: Supported
  4. 123: Supported

Firefox for Android

  1. 124: Supported

QQ Browser

  1. 14.9: Supported

Baidu Browser

  1. 13.52: Supported

KaiOS Browser

  1. 2.5: Partial support
  2. 3: Supported
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