:required

在本文章中

摘要

:required CSS 伪类表示任意 <input> 元素表示任意拥有required属性的 <input> 或 <textarea> 元素使用它. 它允许表单在提交之前容易的展示必填字段并且渲染其外观.

:optional伪类可用于表单可选元素提供外观.

:required { style properties }

查看示例 :invalid .

Specification	Status	Comment
WHATWG HTML Living Standard :required	Living Standard	No change.
HTML5 :required	Recommendation	Defines the semantic regarding HTML and constraint validation.
Selectors Level 4 :required	Working Draft	No change.
CSS Basic User Interface Module Level 3 :required	Candidate Recommendation	Defines the pseudo-class, but not the associated semantic.

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)	未实现	10.0	5.0

另见