wirecake/rollup.config.js

import svelte from "rollup-plugin-svelte";
import resolve from "@rollup/plugin-node-resolve";
import commonjs from "@rollup/plugin-commonjs";
import livereload from "rollup-plugin-livereload";
import postcss from "rollup-plugin-postcss";
import { terser } from "rollup-plugin-terser";
import sveltePreprocessPostcss from "svelte-preprocess-postcss";

const production = !process.env.ROLLUP_WATCH;

export default {
	input: "src/main.js",
	output: {
		sourcemap: true,
		format: "iife",
		name: "app",
		file: "public/out/bundle.js",
	},
	
	plugins: [
		svelte({
			dev: !production,

			// Allow PostCSS to include the CSS output from our SFCs.
			preprocess: { style: sveltePreprocessPostcss() },

			emitCss: true, // Let PostCSS handle it.

			// We can also write CSS to a file.
			//css: (css) => css.write("public/out/svelte.css");
		}),

		postcss({ extract: true }), // Write to a file

		resolve({
			browser: true,
			dedupe: ["svelte"],
		}),
		commonjs(),

		!production && serve(),
		!production && livereload('public') ,// reload when /public changes
		production && terser()
	],
	
	watch: {
		clearScreen: false,
	},
};

function serve() {
	let started = false;

	return {
		writeBundle() {
			if (!started) {
				started = true;

				require("child_process").spawn("npm", ["run", "start", "--", "--dev"], {
					stdio: ["ignore", "inherit", "inherit"],
					shell: true,
				});
			}
		},
	};
}