1. End-to-End
CoffeeScript
Presented by Trevor Burnham
at RailsConf 2011

2. Part I
CoffeeScript!?!?

3. What is CoffeeScript?

4. Do you have to use it?

5. But seriously...

6. Things I’ll cover today:
A brief primer on the CoffeeScript language
How it works with the Rails 3.1 asset
pipeline
Running the same JS/CS code on both the
client and the server

7. And things I won’t:
The CoffeeScript language in depth (that
would take a whole book... available at
http://coffeescript-book.com)
Sprockets 2 (#= require foo)
jQuery UJS ($.rails)

8. CoffeeScript crash course
“Dash rocket” instead of function
Semantic whitespace instead of {}
Implicit parentheses, implicit var scoping

9. Awesome goodies for
Rubyists
Postfix if/unless
Implicit returns
String interpolations

10. Things that feel weird to
Rubyists
Parentheses are not optional on functions
with no arguments
It’s just JavaScript™

11. Things that feel weird to
JavaScripters
CoffeeScript’s of is JavaScript’s in
CoffeeScript’s in is Python’s in
CoffeeScript’s == is JavaScript’s ===

12. Tradeoffs
Debugging (will get better, but currently
kind of a pain)
Changing versions (though it’s been
pretty stable for the last 5 months)
Less documentation (but there is a
book from PragProg...)

13. Even so!
After only a week of using CoffeeScript,
I felt more productive than I ever had in
JavaScript.
The community is awesome.
Learning CoffeeScript might make you think
more deeply about JavaScript.

14. Part II
CoffeeScript in Rails 3.1

15. Let’s make a Rails app!
rails new EndToEnd
cd EndToEnd
rails generate controller User signup
Clone the repo if you want to follow along...
http://github.com/TrevorBurnham/EndToEnd)

16. JavaScripts are assets
New in Rails 3.1, generate controller gives
us a CoffeeScript file automatically:

17. Compound extensions
.html.erb & .html.haml → HTML
.css.scss & .css.sass → CSS
.js.coffee → JavaScript
Want to use a different format? Just rename!
application.js → application.js.coffee

18. Compound extensions
Stylesheets and JavaScripts are automatically
concatenated by Sprockets 2, even in development:
All the CSS and JS is loaded on every page, so it’s
still up to you to isolate controller-specific
functionality.

19. Building a sign-up box

20. Adding JS validations

21. Great, but...
Client-side validations are just there to
provide a friendlier user experience. What
really matters are server-side validations.
Traditionally, we’d do this by using
ActiveRecord, repeating much of the work
we just did...
But there’s another way!

22. Server-side JavaScript!
(And CoffeeScript)
If you’ve got coffee‐script in your
Gemfile, then you’ve already got ExecJS:
https://github.com/sstephenson/execjs
It uses the best available JS environment on
your system. Use therubyracer (or
therubyracer‐heroku) for maximum
portability.

23. No need to rewrite the
same validation code!
ExecJS lets us turn our CoffeeScript
validation code into a Ruby object:

24. A small taste of
what’s to come
Future plugins will make the server-side JS
process smoother in Rails
With jsdom, you can do practically anything
that you could do with client-side JS
(including manipulating HTML with jQuery!)
Validation, templating... anything you’re
duplicating can be done as end-to-end JS.

25. How can you become a
CoffeeScript ninja?
Official site, great overview:
http://coffeescript.org
Nice screencast:
http://peepcode.com/products/coffeescript
Totally unbiased book recommendation:
http://coffeescript-book.com

26. Thanks
Questions?
trevorburnham@gmail.com