n-create-script.ts

const createScriptExec = (script: string) => {
  let instance = null

  return async function execute() {
    if (instance) {
      await kill(instance, 'SIGKILL')
    }

    instance = spawn(script, [], { shell: true })

    return merge<String, String>(
      fromEvent(instance.stderr, 'data').pipe(
        map((data) => message(data.toString(), 'red')),
      ),
      fromEvent(instance.stdout, 'data').pipe(
        map((data) => message(data.toString(), 'cyan')),
      ),
    ).pipe(takeUntil(fromEvent(instance, 'close')))
  }
}

// ...

const executeScript = createScriptExec(script)

// ...

fromEvent(chokidar.watch(process.cwd()), 'all').pipe(
  // ...
  switchMap(executeScript),
  tap(() => console.log(message('Executing...', 'green'))),
  switchMap((obsvr) => {
    return obsvr.pipe(
      tap(console.log),
      reduce(() => null),
    )
  }),
  tap(() => console.log(message('Finished! :fire:', 'green'))),
)