@arcmantle/vite-plugin-sass

A Vite plugin that transforms SASS/SCSS code in tagged template literals and enables importing SASS/SCSS files with proper type assertions.

Features

• 🎨 Tagged Template Literals: Transform sass and scss tagged template literals into compiled CSS
• 📁 File Imports: Import .scss and .sass files with with { type: 'scss' } syntax
• ⚡ Lightning Fast: Uses LightningCSS for minification and optimization
• 🔧 Configurable: Customizable options for minification, root directory, and debug levels
• 🧩 Framework Agnostic: Works with any JavaScript/TypeScript project using Vite
• 📦 Virtual Modules: Efficiently handles SASS imports as virtual modules

Installation

npm install @arcmantle/vite-plugin-sass
# or
pnpm add @arcmantle/vite-plugin-sass
# or
yarn add @arcmantle/vite-plugin-sass
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Usage

Basic Setup

Add the plugin to your vite.config.ts:

import { defineConfig } from 'vite';
import { sassTransformer } from '@arcmantle/vite-plugin-sass';

export default defineConfig({
  plugins: [
    sassTransformer({
      rootDir: './src/styles', // Optional: Root directory for SASS imports
      minify: true,            // Optional: Enable CSS minification (default: true)
      debugLevel: 'silent',    // Optional: Debug level ('silent' | 'error')
    }),
  ],
});
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Tagged Template Literals

Use sass or scss tagged template literals in your TypeScript/JavaScript files:

import { css, LitElement } from 'lit';

const styles = sass`
  $primary-color: #007bff;
  $font-size: 16px;

  .button {
    background-color: $primary-color;
    font-size: $font-size;
    border: none;
    padding: 10px 20px;
    border-radius: 4px;

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

class MyElement extends LitElement {
  static styles = [styles];
  // ... rest of your component
}
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File Imports

Import SASS/SCSS files using the with { type: 'scss' } syntax:

// Import a SCSS file
import styles from './styles.scss' with { type: 'scss' };

// The imported styles will be a CSSStyleSheet object
document.adoptedStyleSheets = [styles];
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styles.scss:

$primary-color: #333;

body {
  font-family: Arial, sans-serif;
  color: $primary-color;
}
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With Lit Elements

Perfect for use with Lit components:

import { LitElement, html, css as sass } from 'lit';
import { customElement } from 'lit/decorators.js';
import globalStyles from './global.scss' with { type: 'scss' };

@customElement('my-component')
export class MyComponent extends LitElement {
  static styles = [
    globalStyles,  // Imported SCSS file
    sass`          // Inline SASS
      @use 'variables';

      :host {
        display: block;
        padding: variables.$base-padding;
      }

      .content {
        background: variables.$background-color;
        border-radius: 8px;
      }
    `,
  ];

  render() {
    return html`<div class="content">Hello World!</div>`;
  }
}
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Configuration Options

SASSTransformerOptions

Option	Type	Default	Description
minify	boolean	true	Enable CSS minification using LightningCSS
rootDir	string	''	Root directory for resolving SASS imports
debugLevel	'error' | 'silent'	'silent'	Debug output level

How It Works

1. Detection: The plugin scans TypeScript/JavaScript files for sass or scss tagged template literals
2. Compilation: SASS code is compiled using the official Dart Sass compiler
3. Minification: Compiled CSS is minified using LightningCSS (if enabled)
4. Transformation: The tagged template literal is replaced with the compiled CSS string
5. Virtual Modules: SASS file imports are handled as virtual modules, creating CSSStyleSheet objects

Supported File Types

Source Files (for transformation)

• .ts - TypeScript files
• .mts - TypeScript modules
• .js - JavaScript files
• .mjs - JavaScript modules

SASS Files (for imports)

• .scss - SASS files with CSS-like syntax
• .sass - SASS files with indented syntax

Example Project Structure

src/
├── styles/
│   ├── _variables.scss
│   ├── _mixins.scss
│   └── base.scss
├── components/
│   ├── button.ts
│   └── card.ts
└── main.ts
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Requirements

• Node.js >= 22
• Vite >= 7.0.0

Dependencies

• sass: Official Dart Sass compiler for SASS compilation
• lightningcss: Fast CSS transformer and minifier
• magic-string: Efficient string manipulation with source maps
• oxc-walker: Fast JavaScript/TypeScript AST walker

License

Apache-2.0

Contributing

This package is part of the Arcmantle Weave monorepo. Contributions are welcome!