:required

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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.

语法

:required { style properties }

例子

查看示例 :invalid .

规范

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.

浏览器兼容

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

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