after和:: after之间有什么区别？ [英] What is the difference between :after and ::after?

问题描述

它说的区别是：after是CSS2，while :: after是CSS3。有没有更重要的区别？

It says the difference is that :after is CSS2, while ::after is CSS3. Are there any more important differences?

（我试过Googling，但冒号似乎抛弃了搜索）

(I've tried Googling, but the colons seem to throw off the search)

推荐答案

伪元素在CSS2中用单个冒号表示，但在CSS3中被改变以建立伪类和伪元素之间的区别。出于兼容性考虑，CSS 1和CSS2中定义的伪元素仍允许使用单个冒号。

Pseudo-elements were denoted with a single colon in CSS2, but have been changed in CSS3 "in order to establish a discrimination between pseudo-classes and pseudo-elements". For compatibility reasons a single colon is still allowed for the pseudo-elements defined in CSS 1 and CSS2.

5.12.3：before和：after伪元素

'：before'和'：after'伪元素可用于在元素内容之前或之后插入生成的内容。

5.12.3 The :before and :after pseudo-elements

The ':before' and ':after' pseudo-elements can be used to insert generated content before or after an element's content.

CSS3 < a>

CSS3

7。伪元素

[...]

7. Pseudo-elements

[...]

伪元素由两个冒号c $ c> :: ），后跟伪元素的名称。

A pseudo-element is made of two colons (::) followed by the name of the pseudo-element.

这个 :: 符号是由当前文档引入的，以便建立伪类和伪 - 元素。 为了与现有样式表兼容，用户代理还必须接受CSS级别1和2中引入的伪元素的前一个冒号符号（即：first-line，：first-letter，：before和：after ）。此兼容性不允许用于本规范中引入的新伪元素。

This :: notation is introduced by the current document in order to establish a discrimination between pseudo-classes and pseudo-elements. For compatibility with existing style sheets, user agents must 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). This compatibility is not allowed for the new pseudo-elements introduced in this specification.

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