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 css from 'rollup-plugin-css-only';
import preprocess from 'svelte-preprocess';
import inlineSvg from 'rollup-plugin-inline-svg';
import replace from '@rollup/plugin-replace';

const production = !process.env.ROLLUP_WATCH;

function serve() {
  let server;

  function toExit() {
    if (server) server.kill(0);
  }

  return {
    writeBundle() {
      if (server) return;
      server = require('child_process').spawn('npm', ['run', 'start', '--', '--dev'], {
        stdio: ['ignore', 'inherit', 'inherit'],
        shell: true
      });

      process.on('SIGTERM', toExit);
      process.on('exit', toExit);
    }
  };
}

export default {
  input: "src/main.js",
  output: {
    sourcemap: true,
    format: "umd",
    name: "app",
    file: "public/build/bundle.js",
  },
  plugins: [
    inlineSvg({
      removeTags: false,
      removingTags: ["title", "desc", "defs", "style"],
    }),
    svelte({
      compilerOptions: {
        // enable run-time checks when not in production
        dev: !production,
      },
      preprocess: preprocess(),
    }),
    // Resolve the public domain path
    replace({ PUBLIC_URL: production ? "/gam-changer" : "" }),

    // we'll extract any component CSS out into
    // a separate file - better for performance
    css({ output: "bundle.css" }),

    // 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(),

    // 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,
  },
};