rollup.config.js

import { babel } from '@rollup/plugin-babel';
import eslint from '@rollup/plugin-eslint';
import { mergician } from 'mergician';
import path from 'node:path';
import pkg from './package.json';
import terser from '@rollup/plugin-terser';

// Settings
// =============================================================================
// Copyright
const currentYear = new Date().getFullYear();
const releaseYear = 2015;

// Output
const entryFile = path.resolve(__dirname, 'src', 'index.js');
const outputFile = path.resolve(__dirname, 'dist', `${pkg.name}.js`);
const outputName = 'canvasSize';

// Banner
const bannerData = [
  `${pkg.name}`,
  `v${pkg.version}`,
  `${pkg.homepage}`,
  `(c) ${releaseYear}${currentYear === releaseYear ? '' : '-' + currentYear} ${pkg.author}`,
  `${pkg.license} license`,
];

// Plugins
const pluginSettings = {
  eslint: {
    exclude: ['node_modules/**', './package.json'],
    throwOnWarning: false,
    throwOnError: true,
  },
  babel: {
    shared: {
      babelHelpers: 'bundled',
      exclude: ['node_modules/**'],
    },
    get esm() {
      return {
        ...this.shared,
        presets: [
          ['@babel/env', { targets: 'defaults and fully supports es6-module' }],
        ],
      };
    },
    get umd() {
      return {
        ...this.shared,
        presets: [['@babel/env', { targets: '>0.3%, ie 11' }]],
      };
    },
  },
  terser: {
    beautify: {
      compress: false,
      mangle: false,
      output: {
        beautify: true,
        comments: /(?:^!|@(?:license|preserve))/,
      },
    },
    minify: {
      compress: true,
      mangle: true,
      output: {
        comments: new RegExp(pkg.name),
      },
    },
  },
};

// Config
// =============================================================================
// Base
const config = {
  input: entryFile,
  output: {
    file: outputFile,
    name: outputName,
    banner: `/*!\n * ${bannerData.join('\n * ')}\n */`,
    sourcemap: true,
  },
  plugins: [eslint(pluginSettings.eslint)],
  watch: {
    clearScreen: false,
  },
};

// Formats
// -----------------------------------------------------------------------------
// ES Module
const esm = mergician({}, config, {
  output: {
    file: config.output.file.replace(/\.js$/, '.esm.js'),
    format: 'esm',
  },
  plugins: [
    ...config.plugins,
    babel(pluginSettings.babel.esm),
    terser(pluginSettings.terser.beautify),
  ],
});

// ES Module (Minified)
const esmMinified = mergician({}, config, {
  output: {
    file: esm.output.file.replace(/\.js$/, '.min.js'),
    format: esm.output.format,
  },
  plugins: [
    ...config.plugins,
    babel(pluginSettings.babel.esm),
    terser(pluginSettings.terser.minify),
  ],
});

// UMD
const umd = mergician({}, config, {
  output: {
    format: 'umd',
  },
  plugins: [
    ...config.plugins,
    babel(pluginSettings.babel.umd),
    terser(pluginSettings.terser.beautify),
  ],
});

// UMD (Minified)
const umdMinified = mergician({}, config, {
  output: {
    file: umd.output.file.replace(/\.js$/, '.min.js'),
    format: umd.output.format,
  },
  plugins: [
    ...config.plugins,
    babel(pluginSettings.babel.umd),
    terser(pluginSettings.terser.minify),
  ],
});

// Exports
// =============================================================================
export default [esm, esmMinified, umd, umdMinified];