config.js

import './src/_server/build/config'

import resolve from 'rollup-plugin-node-resolve';
import replace from 'rollup-plugin-replace';
import commonjs from 'rollup-plugin-commonjs';
// import builtins from 'rollup-plugin-node-builtins'
// import globals from 'rollup-plugin-node-globals'
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';

import preprocess from './src/_server/build/rollup.preprocess'
import sharedVars from './src/_server/build/rollup.vars'

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

export default {
	client: {
		input: config.client.input(),
		output: config.client.output(),
		plugins: [
			replace(Object.assign({
				'process.browser': true,
				'process.server': false,
			}, sharedVars)),
			svelte({
				dev,
				extensions: ['.html', '.svelte', '.svg'],
				hydratable: true,
				emitCss: true,
				preprocess,
			}),
			// globals(),
			// builtins(),
			resolve({ browser: true }),
			commonjs(),

			legacy && babel({
				extensions: ['.js', '.html'],
				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,
			}),
		],
		// TODO: DELETE
		experimentalCodeSplitting: true,
	},

	server: {
		input: config.server.input(),
		output: config.server.output(),
		plugins: [
			replace(Object.assign({
				'process.browser': false,
				'process.server': true,
			}, sharedVars)),
			svelte({
				dev,
				extensions: ['.html', '.svelte', '.svg'],
				generate: 'ssr',
				preprocess,
			}),
			resolve(),
			commonjs(),
		],
		external: Object.keys(pkg.dependencies).concat(
			require('module').builtinModules || Object.keys(process.binding('natives'))
		),
		// TODO: DELETE
		experimentalCodeSplitting: true,
	},

};