Laravel app.js not Found and npm run Failed in New Project

Question

When I run php artisan serve in my new Laravel project, I get a blank page at localhost. The console says Failed to load resource: the server responded with a status of 404 (Not Found) for my app.js. This is my app.js:

import './bootstrap';

require('./bootstrap');

require('./components/HelloReact')

What I've tried: Run npm run dev, upgrade npm to 16.11.1

Any help would be appreciated.