esbuild-sass-plugin

What is esbuild-sass-plugin?

The esbuild-sass-plugin is an npm package that integrates Sass/SCSS compilation into the esbuild bundler. It allows developers to seamlessly compile Sass/SCSS files into CSS during the build process, leveraging the speed and efficiency of esbuild.

What are esbuild-sass-plugin's main functionalities?

Basic Sass/SCSS Compilation

This feature allows you to compile Sass/SCSS files into CSS as part of the esbuild process. The code sample demonstrates how to set up esbuild with the esbuild-sass-plugin to bundle JavaScript and compile Sass/SCSS files.

const esbuild = require('esbuild');
const sassPlugin = require('esbuild-sass-plugin').sassPlugin;

esbuild.build({
  entryPoints: ['src/index.js'],
  bundle: true,
  outfile: 'dist/bundle.js',
  plugins: [sassPlugin()]
}).catch(() => process.exit(1));

Custom Sass Options

This feature allows you to pass custom options to the Sass compiler. The code sample shows how to configure the plugin to include additional paths and enable indented syntax for Sass files.

const esbuild = require('esbuild');
const sassPlugin = require('esbuild-sass-plugin').sassPlugin;

esbuild.build({
  entryPoints: ['src/index.js'],
  bundle: true,
  outfile: 'dist/bundle.js',
  plugins: [sassPlugin({
    includePaths: ['./src/styles'],
    indentedSyntax: true
  })]
}).catch(() => process.exit(1));

Source Maps

This feature enables source map generation for easier debugging of Sass/SCSS files. The code sample demonstrates how to configure esbuild to generate source maps along with the compiled CSS.

const esbuild = require('esbuild');
const sassPlugin = require('esbuild-sass-plugin').sassPlugin;

esbuild.build({
  entryPoints: ['src/index.js'],
  bundle: true,
  outfile: 'dist/bundle.js',
  sourcemap: true,
  plugins: [sassPlugin()]
}).catch(() => process.exit(1));

Other packages similar to esbuild-sass-plugin

sass

The 'sass' package is a standalone Sass compiler that can be used with various build tools. Unlike esbuild-sass-plugin, it does not integrate directly with esbuild but can be used in conjunction with other tools to achieve similar results.

node-sass

The 'node-sass' package is another popular Sass compiler that uses the LibSass library. It is similar to the 'sass' package but is often used in older projects. It does not integrate directly with esbuild but can be used with other build tools.

sass-loader

The 'sass-loader' package is a loader for webpack that compiles Sass/SCSS files. It is similar in functionality to esbuild-sass-plugin but is designed specifically for webpack rather than esbuild.

README

A plugin for esbuild to handle sass & scss files.

Main Features

• defaults to using the css loader
• supports constructable stylesheet modules or dynamic style added to main page
• comes with dart sass but can be easily switched to node-sass
• caching
• PostCSS
• watch mode 🥳

Install

npm i esbuild-sass-plugin

Usage

Just add it to your esbuild plugins:

import {sassPlugin} from "esbuild-sass-plugin";

await esbuild.build({
    ...
    plugins: [sassPlugin()]
});

this will use loader: "css" and your transpiled sass will be included in index.css.

If you specify type: "style" then the stylesheet will be dynamically added to the page.

If you want to use the resulting css text as a string import you can use type: "css-text"

await esbuild.build({
    ...
    plugins: [sassPlugin({
        type: "css-text",
        ... // other options for sass.renderSync(...)
    })]
});

...and in your module do something like

...
import cssText from "./styles.scss";
...
customElements.define("hello-world", class HelloWorld extends HTMLElement {

    constructor() {
        super();
        this.attachShadow({mode: 'open'});
        this.sheet = new CSSStyleSheet();
        this.sheet.replaceSync(cssText);
        this.shadowRoot.adoptedStyleSheets = [this.sheet];
    }
}

Or you can import a lit-element css result using type: "lit-css"

...
import styles from "./styles.scss";
...
@customElement("hello-world")
export default class HelloWorld extends LitElement {

    static styles = styles

    render() {
        ...
    }
}

Look in the test folder for more usage examples.

Options

The options passed to the plugin are a superset of the sass Options.

Option	Type	Default
cache	boolean or Map	true
type	string or array	"css"
implementation	string	"sass"
transform	function	undefined
exclude	regex	undefined

If you want to have different loaders for different parts of your code you can pass type an array.

Each item is going to be:

• the type (one of: css, css-text, lit-css or style)
• a valid picomatch glob, an array of one such glob or an array of two.

e.g.

await esbuild.build({
    ...
    plugins: [sassPlugin({
        type: [                                     // this is somehow like a case 'switch'...
            ["css", "bootstrap/**"],                // ...all bootstrap scss files (args.path) 
            ["style", ["src/nomod/**"]],            // ...all files imported from files in 'src/nomod' (args.importer) 
            ["style", ["**/index.ts","**/*.scss"]], // all scss files imported from files name index.ts (both params)
            ["lit-css"]                             // this matches all, similar to a case 'default'
        ],
    })]
})

NOTE: last type applies to all the files that don't match any matchers.

Exclude Option

Used to exclude paths from the plugin

e.g.

await esbuild.build({
    ...
    plugins: [sassPlugin({
        exclude: /^http:\/\//,  // ignores urls
    })]
})

Transform Option

async (css:string, resolveDir:string?) => string

It's function which will be invoked before passing the css to esbuild or wrapping it in a module.

PostCSS

The simplest use case is to invoke PostCSS like this:

const postcss = require("postcss");
const autoprefixer = require("autoprefixer");
const postcssPresetEnv = require("postcss-preset-env");

esbuild.build({
    ...
    plugins: [sassPlugin({
        async transform(source, resolveDir) {
            const {css} = await postcss([autoprefixer, postcssPresetEnv({stage:0})]).process(source);
            return css;
        }
    })]
});

esbuild

But it can be used to invoke esbuild to do some post processing of the css like in this example where I rely on esbuild to create data urls:

await esbuild.build({
  entryPoints: ["./src/index.ts"],
  outdir: "./out",
  bundle: true,
  format: "esm",
  plugins: [sassPlugin({
    type: "lit-css",
    async transform(css, resolveDir) {
      const {outputFiles:[out]} = await esbuild.build({
        stdin: {
          contents: css,
          resolveDir,
          loader: "css"
        },
        bundle: true,
        write: false,
        format: "esm",
        loader: {
          ".eot": "dataurl",
          ".woff": "dataurl",
          ".ttf": "dataurl",
          ".svg": "dataurl",
          ".otf": "dataurl"
        },
      });
      return out.text;
    }
  })]
});

I am not really happy with this but I am waiting on esbuild to revamp its plugin api before finding another way to achieve the same result.

Look at open-iconic test fixture for a working example.

Use node-sass instead of sass

Remember to add the dependency

npm i esbuild-sass-plugin node-sass

and to specify the implementation in the options:

await esbuild.build({
    ...
    plugins: [sassPlugin({
        implementation: "node-sass",
        ... // other options for sass.renderSync(...)
    })]
});

CACHING

It greatly improves the performance in incremental builds or watch mode.

It has to be enabled with cache: true in the options.

You can pass your own map instead of true if you want to recycle it across different builds.

const pluginCache = new Map();

await esbuild.build({
    ...
    plugins: [sassPlugin({cache: pluginCache})],
    ...
})

Benchmarks

Given 24 x 24 = 576 lit-element files & 576 imported css styles

cache: true

initial build: 2.033s
incremental build: 1.199s     (one ts modified)
incremental build: 512.429ms  (same ts modified again)
incremental build: 448.871ms  (one scss modified)
incremental build: 448.92ms   (same scss modified)

cache: false

initial build: 1.961s
incremental build: 1.986s     (touch 1 ts)
incremental build: 1.336s     (touch 1 ts)
incremental build: 1.069s     (touch 1 scss)
incremental build: 1.061s     (touch 1 scss)

node-sass

initial build: 1.030s
incremental build: 468.677ms  (one ts modified) 
incremental build: 347.55ms   (same ts modified again)
incremental build: 401.264ms  (one scss modified)
incremental build: 364.649ms  (same scss modified)

TODO:

• css in js modules
• refactor the options
• (more?) speed improvements

License

MIT