:optional

摘要

:optional CSS 伪类表示任意没有required属性的 <input>，<select> 或 <textarea> 元素使用它。

/* Selects any optional <input> */
input:optional {
  border: 1px dashed black;
}

它允许表单容易的展示可选字段并且渲染其外观。

注：为必填字段设置外观，请使用 :required伪类。

语法

:optional

规范

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

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! (en-US)

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

:optional

摘要

语法

例子

规范

浏览器兼容性

参见