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 babel from 'rollup-plugin-babel';
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);

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,
			}),
			commonjs(),

			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,
			}),
			resolve(),
			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,
	},
};