Snowpack Closure Compiler Plugin

1.3.2 verified Fri May 01 auth: no javascript maintenance

Snowpack plugin (v1.3.2) that processes JavaScript assets through Google Closure Compiler for minification and static analysis. Requires Node >=8 and Snowpack >=2.0.0. Supports BUNDLE, WHITESPACE_ONLY, SIMPLE, ADVANCED compilation levels, ECMAScript version control via languageIn/languageOut, and custom output file name. Not under active development; last release in 2020.

Common errors

error Error: Cannot find module 'google-closure-compiler' ↓

cause Missing required peer dependency google-closure-compiler.

fix

npm install --save-dev google-closure-compiler

error SyntaxError: Unexpected token 'export' ↓

cause Snowpack config uses ES module syntax but plugin expects CommonJS.

fix

Use module.exports = { ... } instead of export default.

error The "path" argument must be of type string. Received undefined ↓

cause outputFile option not provided or set to undefined when bundle: true.

fix

Set outputFile to a string (e.g., 'main.js') in plugin options.

error Plugin load error: snowpack-plugin-closure-compiler is not a plugin function ↓

cause Plugin imported incorrectly (e.g., using ES import or require with .default).

fix

Use the string reference in plugins array: 'snowpack-plugin-closure-compiler'.

Warnings

deprecated Snowpack itself is deprecated; consider migrating to Vite. ↓

fix Replace Snowpack with Vite and use a corresponding Vite Closure Compiler plugin (e.g., vite-plugin-closure-compiler).

breaking The plugin assumes Snowpack v2 configuration format. Snowpack v3 changed the plugin API. ↓

fix Use with Snowpack v2 only; for v3, check compatibility or switch to another minification plugin.

gotcha If bundle: true, Closure Compiler merges all JS into one file; you must set outputFile to a single value. Multiple output files are not supported. ↓

fix Set bundle: false if you need separate output files per input.

gotcha google-closure-compiler is a heavy dependency (Java-based). Install time and build time may increase significantly. ↓

fix Consider using lighter minifiers like terser or esbuild for faster builds.

deprecated The plugin has not been updated since 2020; languageIn/languageOut options may not support newer ECMAScript features. ↓

fix Use a maintained alternative or update the underlying google-closure-compiler version manually.

Install

npm install snowpack-plugin-closure-compiler

yarn add snowpack-plugin-closure-compiler

pnpm add snowpack-plugin-closure-compiler

Imports

default (plugin)

wrong

// Incorrect: trying to import as ES module
import plugin from 'snowpack-plugin-closure-compiler'

correct

// snowpack.config.js
module.exports = {
  plugins: ['snowpack-plugin-closure-compiler']
}

This is a CommonJS package; use require or string reference in snowpack.config.js.

default (require)

wrong

const scc = require('snowpack-plugin-closure-compiler').default;

correct

const scc = require('snowpack-plugin-closure-compiler');
module.exports = { plugins: [ [scc, { compilationLevel: 'ADVANCED' }] ] }

The plugin exports itself as a function; no default property.

Options interface (TypeScript)

wrong

import { Options } from 'snowpack-plugin-closure-compiler'

correct

// Not exported as types; define inline
interface Options {
  bundle?: boolean;
  outputFile?: string;
  compilationLevel?: string;
  languageIn?: string;
  languageOut?: string;
}

No TypeScript declarations are shipped; use JSDoc or own types.

Quickstart

Configures Snowpack to run Closure Compiler with advanced optimization on all JS files, outputting a single bundle.js.

// Install: npm install --save-dev snowpack snowpack-plugin-closure-compiler google-closure-compiler
// snowpack.config.js
module.exports = {
  mount: {
    src: { url: '/dist' },
    public: { url: '/', static: true },
  },
  plugins: [
    ['snowpack-plugin-closure-compiler', {
      compilationLevel: 'ADVANCED',
      outputFile: 'bundle.js',
      bundle: true,
      languageIn: 'ECMASCRIPT_2020',
      languageOut: 'ECMASCRIPT5',
    }],
  ],
};