I used gem 'bootstrap' to upgrade a Rails project to Bootstrap 4. Then the dropdowns failed due to missing 'popper.js'. According to the documentation I had to add 'bootstrap.bundle.js' which includes 'popper.js' only (https://getbootstrap.com/docs/4.1/getting-started/contents/#js-files).
So far so good until I attempted to add 'bootstrap-select' (latest version 1.13.2) when the same error occured:
bootstrap.self.js?body=1:1554 Uncaught TypeError: Bootstrap dropdown require Popper.js (https://popper.js.org)
at Dropdown.toggle (bootstrap.self.js?body=1:1554)
at HTMLButtonElement.<anonymous> (bootstrap.self.js?body=1:1725)
at Function.each (jquery3.self.js?body=1:355)
at jQuery.fn.init.each (jquery3.self.js?body=1:190)
at jQuery.fn.init._jQueryInterface (bootstrap.self.js?body=1:1710)
at HTMLButtonElement.<anonymous> (bootstrap.self.js?body=1:1882)
at HTMLDocument.dispatch (jquery3.self.js?body=1:5184)
at HTMLDocument.elemData.handle (jquery3.self.js?body=1:4992)
Somehow 'bootstrap-select' ignores 'bootstrap.bundle.js' and if I add 'popper.min.js' or gem 'popper_js' it won't fix the error. Any thoughts pls?