rollup.config.js

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

const path = require('path');
const mode = process.env.NODE_ENV;
const dev = mode === 'development';

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

const aliases = [ ... ]

export default {
	client: {
		input: config.client.input(),
		output: config.client.output(),
		plugins: [
			alias({
				resolve: ['.svelte', '.js'],
				entries: aliases
			}),
			replace({
				'process.browser': true,
				'process.env.NODE_ENV': JSON.stringify(mode)
			}),
			svelte({
				dev,
				hydratable: true,
				emitCss: true
			}),
			resolve({
				browser: true,
				dedupe
			}),
			commonjs(),
			!dev && terser({
				module: true
			})
		],

		onwarn,
	},

	server: {
		input: config.server.input(),
		output: config.server.output(),
		plugins: [
			alias({
				resolve: ['.svelte', '.js'],
				entries: aliases
			}),
			replace({
				'process.browser': false,
				'process.env.NODE_ENV': JSON.stringify(mode)
			}),
			svelte({
				generate: 'ssr',
				dev
			}),
			resolve({
				dedupe
			}),
			commonjs()
		],
		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,
	}
};