rollup.config.js

import babel from 'rollup-plugin-babel';
import commonjs from 'rollup-plugin-commonjs';
import json from 'rollup-plugin-json';
import resolve from 'rollup-plugin-node-resolve';
import postcss from 'rollup-plugin-postcss';
import replace from 'rollup-plugin-replace';
import svelte from 'rollup-plugin-svelte';
import { terser } from 'rollup-plugin-terser';
import config from 'sapper/config/rollup.js';
import pkg from './package.json';

const mode = process.env.NODE_ENV;
const dev = mode === 'development';
const legacy = !!process.env.SAPPER_LEGACY_BUILD;

const onwarn = (warning, onwarn) =>
  (warning.code === 'CIRCULAR_DEPENDENCY' &&
    /[/\\]@sapper[/\\]/.test(warning.message)) ||
  onwarn(warning);

const dedupe = importee =>
  importee === 'svelte' || importee.startsWith('svelte/');

const purgecss = require('@fullhuman/postcss-purgecss')({
  // Specify the paths to all of the template files in your project
  content: ['./src/**/*.html', './src/**/*.svelte', './src/**/*.css'],

  // Include any special characters you're using in this regular expression
  defaultExtractor: content => content.match(/[A-Za-z0-9-_:/]+/g) || []
});

export default {
  client: {
    input: config.client.input(),
    output: config.client.output(),
    plugins: [
      replace({
        'process.browser': true,
        'process.env.NODE_ENV': JSON.stringify(mode)
      }),
      svelte({
        dev,
        hydratable: true,
        emitCss: true
      }),
      resolve({
        browser: true,
        dedupe
      }),
      commonjs(),
      json(),

      legacy &&
        babel({
          extensions: ['.js', '.mjs', '.html', '.svelte'],
          runtimeHelpers: true,
          exclude: ['node_modules/@babel/**'],
          presets: [
            [
              '@babel/preset-env',
              {
                targets: '> 0.25%, not dead'
              }
            ]
          ],
          plugins: [
            '@babel/plugin-syntax-dynamic-import',
            [
              '@babel/plugin-transform-runtime',
              {
                useESModules: true
              }
            ]
          ]
        }),

      !dev &&
        terser({
          module: true
        })
    ],
    onwarn
  },

  server: {
    input: config.server.input(),
    output: config.server.output(),
    plugins: [
      replace({
        'process.browser': false,
        'process.env.NODE_ENV': JSON.stringify(mode)
      }),
      svelte({
        generate: 'ssr',
        dev
      }),
      postcss({
        extract: './static/global.css',
        plugins: [
          require('postcss-import'),
          require('tailwindcss'), // See tailwind.config.js
          require('autoprefixer'),
          require('postcss-fail-on-warn'),
          // Do not purge the CSS in dev mode to be able to play with classes in the browser dev-tools.
          !dev && purgecss,
          !dev &&
            require('cssnano')({
              preset: 'default'
            })
        ].filter(Boolean)
      }),
      resolve({
        dedupe
      }),
      commonjs(),
      json()
    ],
    external: Object.keys(pkg.dependencies).concat(
      require('module').builtinModules ||
        Object.keys(process.binding('natives'))
    ),
    onwarn
  },

  serviceworker: {
    input: config.serviceworker.input(),
    output: config.serviceworker.output(),
    plugins: [
      resolve(),
      replace({
        'process.browser': true,
        'process.env.NODE_ENV': JSON.stringify(mode)
      }),
      commonjs(),
      !dev && terser()
    ],
    onwarn
  }
};