rollup.config.js

import 'dotenv/config';
import babel from '@rollup/plugin-babel';
import commonjs from '@rollup/plugin-commonjs';
import json from '@rollup/plugin-json';
import replace from '@rollup/plugin-replace';
import resolve from '@rollup/plugin-node-resolve';
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;

//if (!dev && !process.env.MAPBOX_ACCESS_TOKEN) {
//	throw new Error('MAPBOX_ACCESS_TOKEN is missing. Please add the token in the .env file before generating the production build.');
//}

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

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

			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(),
		plugins: [
			replace({
				'process.browser': false,
				'process.env.NODE_ENV': JSON.stringify(mode)
			}),
			svelte({
				compilerOptions: {
					dev,
					generate: 'ssr',
					hydratable: true
				},
				emitCss: false
			}),
			resolve({
				dedupe
			}),
			commonjs(),
			json()
		],
		external: [
			'yootils',
			'codemirror',
			...Object.keys(pkg.dependencies || {}).concat(
				require('module').builtinModules || Object.keys(process.binding('natives'))
			)
		],

		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
	}
};