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

问题描述

我刚刚看到一个包含 ::before 标签的 CSS 代码.我查看了 MDN 看看 ::before 是什么是，但我真的不明白.

I just saw a CSS code that included ::before tag. I looked at MDN to see what the ::before is but I really didn't understand it.

有人可以解释它是如何工作的吗?

Can someone explain how it works?

它会在我们通过 CSS 选择之前创建一个 DOM 元素吗?

Does it make a DOM element before what we select by CSS?

推荐答案

这将伪元素与伪类区分开来.

This distinguishes pseudo elements from pseudo classes.

伪类和伪元素的区别在 http://www.d.umn.edu/~lcarlson/csswork/selectors/pseudo_dif.html

The difference between pseudo classes and pseudo elements is described at http://www.d.umn.edu/~lcarlson/csswork/selectors/pseudo_dif.html

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