RFC: Compress atomic class names during CSS extraction about compiled HOT 6 OPEN

We really liked the idea of this RFC and implemented something which works.

Our implementation focuses on @linaria/atomic. But i guess a similar implementation should be possible with in compiled as well.

Because both are build time css-in-js libraries which just manipulate the classnames at runtime.

compiled uses the the ax function and linaria does something similar with a cx function.

Our implementation should be able to handle the safe and "not safe" cases mentioned in the RFC above by @itsdouges without needing to add additional selectors.

You can checkout this article for more details: https://medium.com/engineering-housing/css-pipeline-housing-com-ab8bc09ee4da

The corresponding implementations for linaria's cx function and the function to generate classnames can be found here and here

What we haven't been able to solve for though is long-term caching. how to ensure that we get consistent results across builds. We have done an implementation which requires storing the generated classnames in firebase DB. But we would love to do away with that approach. Looking out for suggestions and comments!

from compiled.

Tangent thought: Explicit disabling of composition/conditional CSS. It means when baked we can simplify it down to something tiny.

from compiled.

I'll add an idea for a step in between: having better mapped shorthands for known properties.
For instance, instead of width: 10px becoming _1p1dangw, why cannot we make it just _w_10?
CSS has a limited dictionary and we could provide compact shorthands for the most used properties.
For values, we could expose a babel config to declare the most used unit (px/em/rem/...) and compact those while preserving hashes for all others.
It might not be a massive saving but given how often things like position: relative, padding-left: Xunit, ... are used, might have sizeable impact on DOM (even if gzip compression mitigates a lot)

from compiled.

Hey @albertogasparin ,

For values, we could expose a babel config to declare the most used unit (px/em/rem/...) and compact those while preserving hashes for all others.

Can you give an example please?

from compiled.

[
  "@compiled/babel-plugin",
  {
    "parserBabelPlugins": ["typescript", "jsx"],
    "mostCommonUnit": "px"
  }
]

This is leveraging the fact that projects generally have a recommended unit of measure that most values adopt (usually px or rem). But thinking more about it, in our case with the push for css vars for spacing, we might find very little benefit as most might end up being padding: var(--spacing-xs) 🙈

from compiled.

not really related but vanilla-extract also does this with the identifier option

from compiled.