selector-pseudo-element-colon-notation

为适用的伪元素选择器指定单冒号或双冒号表示法。

¥Specify single or double colon notation for applicable pseudo-element selectors.

    a::before {}
/**  ↑

 * This notation */

为伪元素选择 :: 表示法是为了区分伪类（现有元素的子类）和伪元素（未在文档树中表示的元素）。

¥The :: notation was chosen for pseudo-elements to establish a discrimination between pseudo-classes (which subclass existing elements) and pseudo-elements (which are elements not represented in the document tree).

然而，为了与现有样式表兼容，用户代理还接受 CSS 级别 1 和 2 中引入的先前的伪元素单冒号表示法（即 :first-line、:first-letter、:before 和 :after）。

¥However, for compatibility with existing style sheets, user agents also accept the previous one-colon notation for pseudo-elements introduced in CSS levels 1 and 2 (namely, :first-line, :first-letter, :before and :after).

fix 选项可以自动修复此规则报告的所有问题。

¥The fix option can automatically fix all of the problems reported by this rule.

选项

¥Options

string："single"|"double"

`"single"`

适用的伪元素必须始终使用单冒号表示法。

¥Applicable pseudo-elements must always use the single colon notation.

以下模式被视为问题：

¥The following patterns are considered problems:

a::before { color: pink; }

a::after { color: pink; }

a::first-letter { color: pink; }

a::first-line { color: pink; }

以下模式不被视为问题：

¥The following patterns are not considered problems:

a:before { color: pink; }

a:after { color: pink; }

a:first-letter { color: pink; }

a:first-line { color: pink; }

input::placeholder { color: pink; }

li::marker { font-variant-numeric: tabular-nums; }

`"double"`

适用的伪元素必须始终使用双冒号表示法。

¥Applicable pseudo-elements must always use the double colon notation.