DIY file watcher with Parcel

runner.ts

// make sure you have @parcel/core and @parcel/config-default
// installed as devDependencies

import {Parcel} from '@parcel/core';
import {spawn, ChildProcessWithoutNullStreams} from 'child_process';

let bundler = new Parcel({
    entries: 'src/index.ts',
    defaultConfig: '@parcel/config-default',
    defaultTargetOptions: { distDir: `${process.cwd()}/dist` },
});

async function main() {
    let cp: ChildProcessWithoutNullStreams;

    await bundler.watch(() => {
        cp?.kill()
        cp = spawn("node",[`${process.cwd()}/dist/index.js`])
        cp.stderr.on('data', (data) => {
            console.log(`stderr: ${data}`);
        })
        cp.stdout.on('data', (data) => {
            console.log(`stdout: ${data}`);
        });
    });
}

main()