Steps to reproduce

Create a new project and create any coffeescript.

Expected behavior

The script using jquery should work.

Actual behavior

Javascript error: $ is not defined.

System configuration

Rails version:
5.1.2
Ruby version:
2.3.3

Any script using jquery will fail, I think it would be expected to work with the included Coffeescript "compiler", as we usually use:
$ ->
define behavior here...

And this will not work, at least on Windows. I detected it using the Firefox debugger showing '$ is not defined', this is jquery not present.
I solved it:

1. Install gem jquery-rails if not installed.
2. Modify the application Gemfile, adding:
   gem 'jquery-rails'
3. Adding to assets/javascript/application.js these lines:
   //= require jquery3
   //= require jquery_ujs
   Just before the //= require rails-ujs.

Now all the coffeescripts work fine.

I think these 3 points should be added to the rails application generator by default.