Using Sprockets to compile javascript assets

By default (in Blacklight 7) the assets generator adds the following things to your application to enable Sprockets to build a javascript bundle:

Added to the Gemfile:

gem 'bootstrap', '~> 4.0'
gem 'popper_js'
gem 'twitter-typeahead-rails', '0.11.1.pre.corejavascript'

These requires are injected into app/assets/javascripts/application.js:

//= require jquery
//= require popper
//= require twitter/typeahead
//= require bootstrap