What do pseudo-classes and pseudo-elements in css mean

Editor to share with you what pseudo-classes and pseudo-elements in css mean, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

Pseudo-classes and pseudo-elements Overview pseudo-classes

Pseudo classes are used to define the special state of an element, which can be used to set the mouse over style, the element to get focus style, the link style, and so on. For example, hover, active, link and so on are all pseudo-classes.

Pseudo element

A pseudo element, also known as a pseudo object, does not exist in the DOM document and is a virtual element. It can be used to represent a child of an element, but that child does not exist in the document tree.

How to distinguish between pseudo classes and pseudo elements

The fundamental difference between pseudo-classes and pseudo-elements is whether new elements are created.

In the W3C, pseudo-classes and pseudo-elements are described as follows: pseudo-classes are used to add special effects to some selectors, while pseudo-elements are used to add special effects to some selectors, that is, pseudo-elements are complementary to elements that cannot be selected through class or id.

Let's take a look at the specific example, when we want to set the text inside the first p tag in the following code to red.

Red

Black

With pseudo-classes, you can try it with simple code:

P:first-child {color:red;}

If we want to set it through pseudo elements, we need to first add a class to the first p tag, and then set it through that class. As follows:

Red

Black

P:first-child {color:red;} above is all the content of the article "what do pseudo-classes and pseudo-elements in css mean?" Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!