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CSS level 4: custom selectors

The possibility to stock some values in variables was one of the main features among others, in my opinion, to the growth of the adoption of the pre-processor. What if we could store selectors? Yes, I will cry. ʘ‿ʘ

It is possible to do something like that:

@custom-selector :--button button, .btn, input[type="submit"];

:--button {
  /* css magic */ 

What we did was store all the elements button and input[type="submit"] and also every element with with btn class in :--button. Then, we declare the style rules in :--button.

Based on this, we can play a bit more and do something like:

@custom-selector :--enter :hover, :focus, .is-hover;
@custom-selector :--active :active, .is-active;

:--button:--enter {
  /* :hover, :focus and .is-hover styles */

:--button:--active {
  /* :active and .is-active styles */

What we did above was:

  • Store the states :hover, :focus and all the elements with the class is-hover in :--enter.
  • Store the states :active and all the elements with the class .is-active in :--active.
  • We put everything together: everything in :--button with :--enter and :--active.

We could also get the same result using our friend matches:

:--button:matches(:hover, :focus, .is-hover) {
  /* :hover, :focus and .is-hover styles */

:--button:matches(:active, .is-active) {
  /* :active and .is-active styles */  

The difference, remembered by my friend Rafael Rinaldi is that our great custom selectors is a choice of preset compared with matches, which makes more easy to reuse.

See the Pen :not selector by Raphael Fabeni (@raphaelfabeni) on CodePen.

Here the link with the example above.

Do you like it? Did I write something stupid? Do you want to improve? Open an issue mentioning the post and let’s talk about it.

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