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HomeEducationAn Introduction to Native CSS Nesting — SitePoint Get hold of US

An Introduction to Native CSS Nesting — SitePoint Get hold of US

Nesting is without doubt one of the core causes for utilizing a CSS preprocessor comparable to Sass. The characteristic has now arrived in customary browser CSS with an analogous syntax. Are you able to drop the preprocessor dependency out of your construct system?

CSS nesting saves typing time and might make the syntax simpler to learn and keep. Up until now, you’ve needed to sort full selector paths like this:

.parent1 .child1,
.parent2 .child1 
  coloration: pink;


.parent1 .child2,
.parent2 .child2 
  coloration: inexperienced;


.parent1 .child2:hover,
.parent2 .child2:hover 
  coloration: blue;

Now, you’ll be able to nest baby selectors inside their guardian, like so:

.parent1, .parent2 

  .child1 
    coloration: pink;
  

  .child2 
    coloration: inexperienced;

    &:hover 
      coloration: blue;
    
  


You’ll be able to nest selectors as deep as you want, however be cautious about going past two or three ranges. There’s no technical restrict to the nesting depth, however it may make code tougher to learn and the ensuing CSS could grow to be unnecessarily verbose.

Till April 2023, no browser understood the nested CSS syntax. You required a construct step with a CSS preprocessor comparable to Sass, Much less, or PostCSS to rework the nested code to the common full-selector syntax. Nesting has now arrived in Chrome 112+ and Safari 16.5+, with Firefox help coming later in 2023 (model 115 has it obtainable behind a characteristic flag).

Are you able to drop your preprocessor in favor of native nesting? As ordinary … it relies upon. Native nesting syntax has advanced over the previous couple of years. It’s superficially much like Sass — which is able to please most internet builders — however don’t anticipate all SCSS code to work straight as you anticipate.

Native CSS Nesting Guidelines

You’ll be able to nest any selector inside one other, however it should begin with a logo comparable to &, . (for a HTML class), # (for a HTML id), @ (for a media question), :, ::, *, +, ~, >, or [. In other words, it cannot be a direct reference to an HTML element. This code is invalid and the <p> selector is not parsed:

.parent1 

  
  p 
    color: blue;
  


The easiest way to fix this is to use an ampersand (&), which references the current selector in an identical way to Sass:

.parent1 

  
  & p 
    color: blue;
  


Alternatively, you could use one of these:

  • > p — but this would style direct children of .parent1 only

  • :is(p) — but :is() uses the specificity of the most specific selector

  • :where(p) — but :where() has zero specificity

They would all work in this simple example, but you could encounter specificity issues later with more complex stylesheets.

The & also allows you to target pseudo-elements and pseudo-classes on the parent selector. For example:

p.my-element 

  &::after 

  &:hover 

  &:target 


If you don’t use &, you’ll be targeting all child elements of the selector and not p.my-element itself. (The same would occur in Sass.)

Note that you can use an & anywhere in the selector. For example:

.child1 

  .parent3 & 
    color: red;
  


This translates to the following non-nested syntax:

.parent3 .child1  color: red; 

You can even use multiple & symbols in a selector:

ul 

  & li & 
    color: blue;
  


This would target nested <ul> elements (ul li ul), but I’d recommend against using this if you want to keep your sanity!

Finally, you can nest media queries. The following code applies a cyan color to paragraph elements — unless the browser width is at least 800px, when they become purple:

p 

  color: cyan;

  @media (min-width: 800px) 
    color: purple;
  


Native CSS Nesting Gotchas

Native nesting wraps parent selectors in :is(), and this can lead to differences with Sass output.

Consider the following nested code:

.parent1, #parent2 
  .child1 

This effectively becomes the following when it’s parsed in a browser:

:is(.parent1, #parent2) .child1 

A .child1 element inside .parent1 has a specificity of 101, because :is() uses the specificity of its most specific selector — in this case, the #parent2 ID.

Sass compiles the same code to this:

.parent1 .child1,
#parent2 .child1 

In this case, a .child1 element inside .parent1 has a specificity of 002, because it matches the two classes (#parent2 is ignored). Its selector is less specific than the native option and has a greater chance of being overridden in the cascade.

You may also encounter a subtler issue. Consider this:

.parent .child 

  .grandparent & 


The native CSS equivalent is:

.grandparent :is(.parent .child) 

This matches the following mis-ordered HTML elements:

<div class="parent">
  <div class="grandparent">
    <div class="child">MATCH</div>
  </div>
</div>

MATCH becomes styled because the CSS parser does the following:

  1. It finds all elements with a class of child which also have an ancestor of parentat any point up the DOM hierarchy.

  2. Having found the element containing MATCH, the parser checks whether it has an ancestor of grandparent — again, at any point up the DOM hierarchy. It finds one and styles the element accordingly.

This is not the case in Sass, which compiles to this:

.grandparent .parent .child 

The HTML above is not styled, because the element classes don’t follow a strict grandparent, parent, and child order.

Finally, Sass uses string replacement, so declarations such as the following are valid and match any element with an outer-space class:

.outer 
  &-space  color: black; 

Native CSS ignores the &-space selector.

Do You Still Require a CSS Preprocessor?

In the short term, your existing CSS preprocessor remains essential. Native nesting is not supported in Firefox or Chrome/Safari-based browsers, which have not received updates in a few months.

The Sass development team has announced they will support native CSS nesting in .css files and output the code as is. They will continue to compile nested SCSS code as before to avoid breaking existing codebases, but will start to emit :is() selectors when global browser support reaches 98%.

I suspect preprocessors such as PostCSS plugins will expand nested code for now but remove the feature as browser support becomes more widespread.

Of course, there are other good reasons to use a preprocessor — such as bundling partials into a single file and minifying code. But if nesting is the only feature you require, you could certainly consider native CSS for smaller projects.

Summary

CSS nesting is one of the most useful and practical preprocessor features. The browser vendors worked hard to create a native CSS version which is similar enough to please web developers. There are subtle differences, though, and you may encounter unusual specificity issues with (overly) complex selectors, but few codebases will require a radical overhaul.

Native nesting may make you reconsider your need for a CSS preprocessor, but they continue to offer other benefits. Sass and similar tools remain an essential part of most developer toolkits.

To delve more into native CSS nesting, check out the W3C CSS Nesting Specification.


#Introduction #Native #CSS #Nesting #SitePoint

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