LAS Engine (lasgine)

JIT engine for LAS CSS. Scans your project, detects used utility classes, and outputs only the CSS you need.

Quick Start

npm install -D lasgine lascss
pnpm add -D lasgine lascss
yarn add -D lasgine lascss

import fs from "fs";
import { LasEngine } from "lasgine";

const engine = new LasEngine({
  scanDirs: ["src"], // extensions/cssExtensions/ignoreDirs merge with defaults
});

engine.init(["./src"]); // initial scan
const css = engine.getCSS(); // base + JIT + user CSS (purged)
fs.writeFileSync("public/las.css", css);

How It Works

• Reads base/meta/utility CSS from the lascss package.
• Extracts breakpoints, variants, colors, and opacities from meta custom properties.
• Scans scanDirs, generates CSS for the classes you actually use.
• updateFile(path) incrementally processes changed files; getCSS() always returns up-to-date output.

API & Options

• scanDirs: Directories to scan. Default: ["src"].
• extensions: Content extensions. Default: .html,.js,.jsx,.ts,.tsx,.vue,.svelte (+ yours).
• cssExtensions: CSS/SCSS extensions for @apply and purge. Default: .css,.scss,.sass,.less,.pcss,.styl,.stylus.
• ignoreDirs: Directories to ignore. Default: node_modules, dist, .git, build, .next, .nuxt, coverage.
• getCSS(): Combined base + JIT + user CSS (after unused purge).
• getCssFileInfo(css): Size label (kB/MB).
• getWatchedCSSFiles(): CSS files watched for apply/purge.
• reset(): Clears internal state and caches.

Notes

• The lascss package must be installed; base/meta/utility assets are read from it.
• You can write the output yourself or let the bundler plugins (las-vite, las-webpack) inject it automatically.