Recker Swartz

Updated:
Rails 6 with Bootstrap and configured with Webpack

Step 1:
yarn add bootstrap jquery popper.js

Step 2:
in config/webpack/environment.js add the following:

const { environment } = require('@rails/webpacker')

const webpack = require('webpack')
environment.plugins.append('Provide', new webpack.ProvidePlugin({
  $: 'jquery',
  jQuery: 'jquery',
  Popper: ['popper.js', 'default']
}))

module.exports = environment

Step 3:
in app/javascript/packs/application.js add the following:

require("bootstrap/dist/js/bootstrap")

note: doesn't need to import jquery , popper once initialized as webpacker plugin

step 4:
in app/assets/stylesheets/application.css add the following:
@import "bootstrap/scss/bootstrap";
or
*= require bootstrap/scss/bootstrap
note: rails-sass can pick file from node modules
This get bootstrap 4 up and running with Rails 6 Beta and webpack!