rollup.config.js

import svelte from 'rollup-plugin-svelte'
import commonjs from '@rollup/plugin-commonjs'
import resolve from '@rollup/plugin-node-resolve'
import livereload from 'rollup-plugin-livereload'
import { terser } from 'rollup-plugin-terser'
import sveltePreprocess from 'svelte-preprocess'
import typescript from '@rollup/plugin-typescript'
import css from 'rollup-plugin-css-only'
import scss from 'rollup-plugin-scss'
import alias from '@rollup/plugin-alias'

import { serve } from './rollup.utils'

const production = !process.env.ROLLUP_WATCH

export default {
  input: 'src/main.ts',
  output: {
    sourcemap: true,
    format: 'iife',
    name: 'app',
    file: 'public/build/bundle.js'
  },
  plugins: [
    svelte({
      preprocess: sveltePreprocess({
        sourceMap: !production,
        scss: {
          importer: [
            // scssAliases({
            //   'src/styles/': __dirname + '/src/styles/'
            // })
          ],
          includePaths: ['root']
        }
      }),
      compilerOptions: {
        // enable run-time checks when not in production
        dev: !production
      }
    }),
    // we'll extract any component CSS out into
    // a separate file - better for performance
    css({ output: 'bundle.css' }),
    scss({
      watch: 'src'
    }),

    // If you have external dependencies installed from
    // npm, you'll most likely need these plugins. In
    // some cases you'll need additional configuration -
    // consult the documentation for details:
    // https://github.com/rollup/plugins/tree/master/packages/commonjs
    resolve({
      browser: true,
      dedupe: ['svelte']
    }),
    commonjs(),
    typescript({
      sourceMap: !production,
      inlineSources: !production
    }),

    alias({
      entries: [
        // If you add a new top-level-folder besides src which you want to use, add it here
        { find: /^@(\/|$)/, replacement: `${__dirname}/src/` }
      ]
    }),

    // In dev mode, call `npm run start` once
    // the bundle has been generated
    !production && serve(),

    // Watch the `public` directory and refresh the
    // browser on changes when not in production
    !production && livereload('public'),

    // If we're building for production (npm run build
    // instead of npm run dev), minify
    production && terser()
  ],
  watch: {
    clearScreen: false
  }
}