css3 - css中伪类选择器跟伪对象选择器区别是啥

Question

我试过例如：p::first-letter 跟 p:first-letter 设置一段文字一个字的字体；两种方法 效果一模一样啊~！那么伪类选择器跟伪对象选择器区别是啥？？？

Answer 1

Pseudo class should be written as :weilei according to current specifications.
Pseudo element should be written as ::weiyuansu

according to current specifications.

But when the specification was not clear in the past, pseudo-elements and pseudo-classes were written as: weiyuansu :weilei
In order to be compatible with the past writing method
, your pseudo-elements written in quotation marks can also be parsed

The main pseudo elements are:
E:first-letter/E::first-letter E:first-line/E::first-line E:before/E::before E:after/E:: after E::placeholder E::selection

The main pseudo-classes are:
E:link E:visited E:hover E:active E:focus E:lang(fr) E:not(s) E:root E:first-child E:last- child E:only-child E:nth-child(n) E:nth-last-child(n) E:first-of-type E:last-of-type E:only-of-type E:nth-of -type(n) E:nth-last-of-type(n) E:empty E:checked E:enabled E:disabled E:target @page:first @page:left @page:right

Single colon and double colon are mainly to distinguish between pseudo elements and pseudo classes

The difference between the two Introduction to the Desert Illustration css3 p69

Pseudo-classes generally reflect the state or attributes of an element that cannot be easily or reliably detected in CSS;
Pseudo-elements represent some kind of document structure outside the DOM