Bootstrap 4 has now been released and its time to try it on your Laravel projects so here is the simple way to upgrade your existing Bootstrap 3 to Bootstrap 4, this can be used on existing and new projects. Just be careful with your old projects as there are a lot of breaking changes.
npm uninstall --save-dev bootstrap-sass
npm install --save-dev bootstrap@^4.0.0-beta popper.js
window.$ = window.jQuery = require('jquery');
require('bootstrap-sass');
Replace this with the following. window.$ = window.jQuery = require('jquery');
window.Popper = require('popper.js');
require('bootstrap');
bootstrap-sass/assets/stylesheets/bootstrap
//to
bootstrap/dist/css/bootstrap
//Now Run
npm run dev
You should now see the upgraded Bootstrap changes in your Laravel project. Here is a YouTube video which may help if your stuck.