:required - CSS（层叠样式表） 编辑

摘要

:required  CSS 伪类 表示任意设置了required属性的<input>，<select>, 或 <textarea>元素。 这个伪类对于高亮显示在提交表单之前必须具有有效数据的字段非常有用。

注意：:optional伪类选中'可选的'表单字段。

语法

:required

例子

查看示例 :invalid .

规范

Specification	Status	Comment
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	Recommendation	Defines the pseudo-class, but not the associated semantic.

浏览器兼容

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

• Desktop
• Mobile

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

参见

• :optional, :invalid, :valid