Summary
The :required CSS pseudo-class represents any <input> element that has the required attribute set on it. This allows forms to easily indicate which fields must have valid data before the form can be submitted.
The :optional pseudo-class may be used to provide an appearance for optional form fields.
Examples
See :invalid for an example.
Specifications
| Specification | Status | Comment |
|---|---|---|
| WHATWG HTML Living Standard The definition of ':required' in that specification. |
Living Standard | No change. |
| HTML5 The definition of ':required' in that specification. |
Recommendation | Defines the semantic regarding HTML and constraint validation. |
| Selectors Level 4 The definition of ':required' in that specification. |
Working Draft | No change. |
| CSS Basic User Interface Module Level 3 The definition of ':required' in that specification. |
Candidate Recommendation | Defines the pseudo-class, but not the associated semantic. |
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | 10.0 | 4.0 (2) | 10 | 10.0 | 5.0 |
| Feature | Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|
| Basic support | ? | 4.0 (2) | Not supported | 10.0 | 5.0 |