rics

Core compiler for the rics CSS preprocessor. A fast, lightweight SCSS-like preprocessor that runs anywhere JavaScript runs.

Installation

npm install rics

Usage

import { compile } from "rics";

const css = compile(`
$primary: #f43f5e;

.button {
  background: $primary;

  &:hover {
    background: darken($primary, 10%);
  }
}
`);

API

compile(input, config?)

Compiles rics/SCSS input to CSS.

const css = compile(input);

compileWithDetails(input, config?)

Returns full compilation result including errors, warnings, and stats.

const result = compileWithDetails(input);

console.log(result.css);
console.log(result.errors); // CompileError[]
console.log(result.warnings); // CompileWarning[]
console.log(result.stats); // { duration, rules, iterations, inputSize, outputSize }

compileAsync(input, config?)

Non-blocking compilation for large inputs.

const result = await compileAsync(largeStylesheet);

Configuration

compile(input, {
  timeout: 5000, // Max compilation time (ms)
  maxIterations: 10000, // Max loop iterations
  maxNestingDepth: 64, // Max selector nesting
  minify: false, // Minify output
  strictMode: false, // Throw on first error
});

Features

• Variables and math operations
• Nesting with & parent selector
• Mixins with parameters, default values, and named arguments
• Custom functions with @function and @return
• Control flow: @if, @else, @for, @each, @while
• Color functions: darken, lighten, mix, saturate, and more
• String interpolation with #{}
• Native CSS pass-through for modern features

Benchmarks

Auto-generated. Run pnpm bench in the benchmarks folder to regenerate.

Performance (ops/sec, higher is better)

Preprocessor	ops/sec	Comparison
rics	897	fastest
stylus	334	2.7x slower
sass	279	3.2x slower
less	221	4.1x slower

Package Size (minzipped, smaller is better)

Package	Size	Dependencies	Comparison
rics	12.7 KB	0	smallest
less	49.0 KB	0	4x larger
stylus	82.8 KB	5	7x larger
sass	686.0 KB	1	54x larger

License

MIT

Built by Better Lyrics