From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:40:17 -0500 Subject: initial commit --- files/zh-cn/web/css/_colon_optional/index.html | 123 +++++++++++++++++++++++++ 1 file changed, 123 insertions(+) create mode 100644 files/zh-cn/web/css/_colon_optional/index.html (limited to 'files/zh-cn/web/css/_colon_optional') diff --git a/files/zh-cn/web/css/_colon_optional/index.html b/files/zh-cn/web/css/_colon_optional/index.html new file mode 100644 index 0000000000..601a0336da --- /dev/null +++ b/files/zh-cn/web/css/_colon_optional/index.html @@ -0,0 +1,123 @@ +--- +title: ':optional' +slug: 'Web/CSS/:optional' +translation_of: 'Web/CSS/:optional' +--- +

{{ CSSRef() }}

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摘要

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:optional CSS 伪类 表示任意没有{{ htmlattrxref("required","input") }}属性的 {{ HTMLElement("input") }},{{HTMLElement("select")}} 或  {{ HTMLElement("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。

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+

注:为必填字段设置外观,请使用 {{ cssxref(":required") }}伪类。

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+ +

语法

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{{csssyntax}}
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例子

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查看{{ cssxref(":invalid") }} 示例。

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规范

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SpecificationStatusComment
{{ SpecName('HTML WHATWG', '#selector-optional', ':optional') }}{{ Spec2('HTML WHATWG') }}No change.
{{ SpecName('HTML5 W3C', '#selector-optional', ':optional') }}{{ Spec2('HTML5 W3C') }}Defines the semantic regarding HTML and constraint validation.
{{ SpecName('CSS4 Selectors', '#opt-pseudos', ':optional') }}{{ Spec2('CSS4 Selectors') }}No change.
{{ SpecName('CSS3 Basic UI', '#pseudo-required-value', ':optional') }}{{ Spec2('CSS3 Basic UI') }}Defines the pseudo-class, but not the associated semantic.
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浏览器兼容性

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{{ CompatibilityTable() }}

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FeatureChromeFirefox (Gecko)Internet ExplorerOperaSafari
Basic support10.0{{ CompatGeckoDesktop("2") }}1010.05.0
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FeatureAndroidFirefox Mobile (Gecko)IE MobileOpera MobileSafari Mobile
Basic support{{ CompatUnknown() }}{{ CompatGeckoMobile("2") }}{{ CompatNo() }}10.05.0
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参见

+ + -- cgit v1.2.3-54-g00ecf