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 typescript from "rollup-plugin-typescript2";
import svelteSVG from "rollup-plugin-svelte-svg";

import config from "sapper/config/rollup.js";
import pkg from "./package.json";

const svelteOptions = require("./svelte.config.js");

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

const onwarn = (warning, onwarn) =>
	(warning.code === 'MISSING_EXPORT' && /'preload'/.test(warning.message)) ||
	(warning.code === 'CIRCULAR_DEPENDENCY' && /[/\\]@sapper[/\\]/.test(warning.message)) ||
	(warning.code === 'THIS_IS_UNDEFINED') ||
	onwarn(warning);

module.exports = {
  client: {
    input: config.client.input().replace(/\.js$/, ".ts"),
    output: config.client.output(),
    preserveEntrySignatures: false,
    plugins: [
      replace({
        "process.browser": true,
        "process.env.NODE_ENV": JSON.stringify(mode),
      }),
      svelte(svelteOptions),
      resolve({
        browser: true,
      }),
      commonjs(),
      typescript(),
      svelteSVG(),

      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,
        }),
    ],

    onwarn,
  },

  server: {
    /**
     *? config.server.input returns an object instead of a string like the client does. Not sure if this is intended so I have it check the type before calling replace()
     */
    input: (typeof config.server.input() === "string"
      ? config.server.input()
      : config.server.input().server
    ).replace(/\.js$/, ".ts"),
    output: config.server.output(),
    preserveEntrySignatures: false,
    plugins: [
      replace({
        "process.browser": false,
        "process.env.NODE_ENV": JSON.stringify(mode),
      }),
      svelte({
        ...svelteOptions,
        generate: "ssr",
      }),
      resolve(),
      commonjs(),
      typescript(),
      svelteSVG({ generate: "ssr" }),
    ],
    external: Object.keys(pkg.dependencies).concat(
      require("module").builtinModules ||
        Object.keys(process.binding("natives"))
    ),

    onwarn,
  },
  /**
   ** uncomment #swts to enable typescript for the service worker.
   ** TS seems to work fine with the service worker but when I switch it to TS there's like 9 type errors that I'm just not trying to deal with. <3
   */
  // serviceworker: {
  //   //#swts input: config.serviceworker.input().replace(/\.js$/, '.ts')
  //   input: config.serviceworker.input(),
  //   output: config.serviceworker.output(),
  //   plugins: [
  //     resolve(),
  //     replace({
  //       "process.browser": true,
  //       "process.env.NODE_ENV": JSON.stringify(mode),
  //     }),
  //     commonjs(),
  //     //#swts typescript()
  //     !dev && terser(),
  //   ],

  //   onwarn,
  // },
};