rollup.config.js

import path from 'path'
import resolve from '@rollup/plugin-node-resolve'
import replace from '@rollup/plugin-replace'
import commonjs from '@rollup/plugin-commonjs'
import url from '@rollup/plugin-url'
import svelte from 'rollup-plugin-svelte'
import babel from '@rollup/plugin-babel'
import { terser } from 'rollup-plugin-terser'
import config from 'sapper/config/rollup.js'
import pkg from './package.json'
const { preprocess } = require('./svelte.config')

import dotenv from 'dotenv'
dotenv.config()

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

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

export default {
  client: {
    input: config.client.input(),
    output: config.client.output(),
    plugins: [
      replace({
        'process.browser': true,
        'process.env.NODE_ENV': JSON.stringify(mode) 
      }),
      svelte({
        preprocess,
        dev,
        hydratable: true,
        emitCss: true
      }),
      url({
        sourceDir: path.resolve(__dirname, 'src/node_modules/images'),
        publicPath: '/client/' 
      }),
      resolve({
        browser: true,
        dedupe: ['svelte'] 
      }),
      commonjs(),

      legacy && babel({
        extensions: ['.js', '.mjs', '.html', '.svelte'],
        babelHelpers: 'runtime',
        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 })
    ],

    preserveEntrySignatures: false,
    onwarn,
  },

  server: {
    input: config.server.input(),
    output: { ...config.server.output(), exports: 'default' },
    plugins: [
      replace({
        'process.browser': false,
        'process.env.NODE_ENV': JSON.stringify(mode) 
      }),
      svelte({
        preprocess,
        generate: 'ssr',
        hydratable: true,
        dev
      }),
      url({
        sourceDir: path.resolve(__dirname, 'src/node_modules/images'),
        publicPath: '/client/',
        emitFiles: false // already emitted by client build
      }),
      resolve({ dedupe: ['svelte'] }),
      commonjs()
    ],
    external: Object.keys(pkg.dependencies).concat(require('module').builtinModules),

    preserveEntrySignatures: 'strict',
    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()
    ],

    preserveEntrySignatures: false,
    onwarn,
  }
}