:is() Pseudo-Class

In CSS the :is() selector is a pseudo-class function, as you can see () in the end. The :is() pseudo-class selector takes a list of the selector as its argument. It allows us to write long and complex statements more compactly. So in this article, we are going to explain :is() pseudo-class with examples.

I. Why use :is pseudo-class?

While writing compound selectors, it sometimes turns into a complex one. And with these complex selectors, we need to be more careful.

header h1, header a, header p, header .btn, header .card {

color: red; 

} 

The above code is very lengthy, and it can be annoying if we want to make a change here.

So instead of writing a whole bunch of selectors, you could use :is(). It makes your code look cleaner and increases its legibility. Also, with :is(), we need to change only one selector instead of many.

header :is(h1, a, p, .btn, .card){

color: red;

}

We are just putting the parent selector once, and then we are passing the list of selectors in the argument. The :is() pseudo-class increases the legibility of your code. Also, with :is(), we need to change only one selector instead of many.

II. Invalid Selectors

If you put an invalid selector like :a in the big chain of selectors, the browser will ignore the whole chain of selectors and throw your entire block into the garbage.

header h1, header :a, header :p {

color: red; //the color of the h1 heading will not change to red.

} 

But when using :is() pseudo-class, instead of ignoring the whole list of selectors, the browser will only skip the incorrect or invalid one, and the rest will work fine.

header :is(h1, :a, :p){

color: red; //the color of the h1 heading will change to red.

}

III. Specificity of :is()

According to W3C Working Draft:

The specificity of the :is() pseudo-class is replaced by the specificity of its most specific argument. Thus, a selector is written with :is() does not necessarily have equivalent specificity to the equivalent selector written without :is().

That means the specificity of :is() is automatically set to the most specific items in the argument list.

To understand the above statement entirely, let’s take an example.

header :is(h1, .list) // This has the higher preference

//then this, even if it comes later

header h1{........}

The :is() has a higher preference because of its heavier selector, which is .list. Also, if .list is not there in the argument list, then the preferences of the normal selector and the :is() will remain the same.

Hopefully, the above write-up was enough for you to understand :is pseudo-class entirely. If you have any questions or suggestions, you can write to us in the comment section below.

Happy Coding!

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