CSS Pseudo-elements and CSS Pseudo-classes Demystified

Hey there, today I picked the topic CSS Pseudo-elements and Pseudo-classes, You may ask why? it's because I was little bit confused with the pseudo-elements and pseudo-class. So I just want to make clear about this today and thought to share my learnings here.

Pseudo-elements and Pseudo-classes are some of the cool concepts of CSS. So learning it will surely help you when you want to design with CSS.

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So what is Pseudo-element?

A CSS pseudo-element is used to style specified parts of an element.

For example, it can be used to:

• Style the first letter, or line, of an element
• Insert content before, or after, the content of an element

Syntax

The syntax of pseudo-elements:

selector::pseudo-element {
  property: value;
}

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And what are Pseudo-classes?

A pseudo-class is used to define a special state of an element.

For example, it can be used to:

• Style an element when a user mouses over it
• Style visited and unvisited links differently
• Style an element when it gets focus

Syntax

The syntax of pseudo-classes:

selector:pseudo-class {
  property: value;
}

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Can you find the difference in syntax?

Notice the double colon notation - ::first-line versus :first-line

The single-colon notation for pseudo-classes and double-colon notation used for pseudo-elements in CSS3.

This was an attempt from W3C to distinguish between pseudo-classes and pseudo-elements.

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Examples of CSS Pseudo Elements

Selector	Example	Description
::after	p::after	Insert something after the content of each ``` ``` element
::before	p::before	Insert something before the content of each ``` ``` element
::first-letter	p::first-letter	Selects the first letter of each ``` ``` element
::first-line	p::first-line	Selects the first line of each ``` ``` element
::marker	::marker	Selects the markers of list items
::selection	p::selection	Selects the portion of an element that is selected by a user

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Examples of CSS Pseudo Classes

Selector	Example	Example description
:active	a:active	Selects the active link
:checked	input:checked	Selects every checked `````` element
:disabled	input:disabled	Selects every disabled `````` element
:empty	p:empty	Selects every ``` ``` element that has no children
:enabled	input:enabled	Selects every enabled `````` element
:first-child	p:first-child	Selects every ``` ``` elements that is the first child of its parent
:first-of-type	p:first-of-type	Selects every ``` ``` element that is the first ``` ``` element of its parent
:focus	input:focus	Selects the `````` element that has focus
:hover	a:hover	Selects links on mouse over
:in-range	input:in-range	Selects `````` elements with a value within a specified range
:invalid	input:invalid	Selects all `````` elements with an invalid value
:lang(language)	p:lang(it)	Selects every ``` ``` element with a lang attribute value starting with "it"
:last-child	p:last-child	Selects every ``` ``` elements that is the last child of its parent
:last-of-type	p:last-of-type	Selects every ``` ``` element that is the last ``` ``` element of its parent
:link	a:link	Selects all unvisited links
:not(selector)	:not(p)	Selects every element that is not a ``` ``` element
:nth-child(n)	p:nth-child(2)	Selects every ``` ``` element that is the second child of its parent
:nth-last-child(n)	p:nth-last-child(2)	Selects every ``` ``` element that is the second child of its parent, counting from the last child
:nth-last-of-type(n)	p:nth-last-of-type(2)	Selects every ``` ``` element that is the second ``` ``` element of its parent, counting from the last child
:nth-of-type(n)	p:nth-of-type(2)	Selects every ``` ``` element that is the second ``` ``` element of its parent
:only-of-type	p:only-of-type	Selects every ``` ``` element that is the only ``` ``` element of its parent
:only-child	p:only-child	Selects every ``` ``` element that is the only child of its parent
:optional	input:optional	Selects `````` elements with no "required" attribute
:out-of-range	input:out-of-range	Selects `````` elements with a value outside a specified range
:read-only	input:read-only	Selects `````` elements with a "readonly" attribute specified
:read-write	input:read-write	Selects `````` elements with no "readonly" attribute
:required	input:required	Selects `````` elements with a "required" attribute specified
:root	root	Selects the document's root element
:target	#news:target	Selects the current active #news element (clicked on a URL containing that anchor name)
:valid	input:valid	Selects all `````` elements with a valid value
:visited	a:visited	Selects all visited links

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References

1. https://www.w3schools.com/css/css_pseudo_elements.asp
2. https://www.w3schools.com/css/css_pseudo_classes.asp
3. https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_blocks/Selectors/Pseudo-classes_and_pseudo-elements

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Hope you get an idea about pseudo-elements and pseudo-classes. Thanks for taking your time and reading this article. This article was originally published in my blog.

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