If you have a look at the default application.js file generated by Rails, you’ll see //= require jquery_ujs. You might know exactly what this require is for, but if you’re like us you know you need it but have only a vague idea of what it’s responsible for.

Maybe you’ve looked at that line and thought, “I should really figure out what that does someday.” Well, for us, today is that day. Please enjoy A Tour of Rails’ jQuery UJS.