select2-rails gem is not working on Rails4

Question

I have tried given documentation for the select2-rails gem, but my browser console still throws an error.

Uncaught TypeError: $(...).select2 is not a

Answer 1

On rails 5 using CoffeeScript and turbolinks I had to use the line:
$(document).on "turbolinks:load", -> before everything so that the code gets executed when the desired page with the select tag is loaded.