If you use php artisan serve for local development in Laravel and npm run watch to autocompile SCSS and JS, here’s a convenient NPM command to launch both simultaneously. I got it from a StackOverflow thread.

{
    "private": true,
    "scripts": {
        "start": "(start npm run watch && start php artisan serve) || (npm run watch & php artisan serve)", <-- This one
        "dev": "npm run development",
        ...
    },