rollup.config.js

import svelte from 'rollup-plugin-svelte';
import resolve from 'rollup-plugin-node-resolve';
import commonjs from 'rollup-plugin-commonjs';
import { terser } from 'rollup-plugin-terser';
import typescript from 'rollup-plugin-typescript2';
import { preprocess, createEnv, readConfigFile } from '@pyoner/svelte-ts-preprocess';

const production = !process.env.ROLLUP_WATCH;

const env = createEnv();
const compilerOptions = readConfigFile(env);
const opts = {
    env,
    compilerOptions: {
        ...compilerOptions,
        allowNonTsExtensions: true
    }
};

export default {
    input: 'src/main.ts',
    output: {
        sourcemap: true,
        format: 'iife',
        name: 'app',
        file: 'public/bundle.js'
    },
    plugins: [
        svelte({
            dev: !production,
            css: css => {
                css.write('public/bundle.css');
            },
            preprocess: preprocess(opts)
        }),
        resolve(),
        commonjs(),
        typescript(),
        production && terser()
    ]
};