CoffeeScript is a programming language that compiles to JavaScript, cleaning up JavaScript's syntax and making it more readable. It uses Ruby- and Python-inspired syntax like no semicolons or brackets, and tab indentation. To use CoffeeScript, install Node.js, npm, and CoffeeScript, then write code in CoffeeScript files that will compile to JavaScript for use in browsers or frameworks like Rails.

1. CoffeeScript
Write javascript easier
Monday, January 24, 2011

2. Javascript
• Great language
• 60-70% of the code I write now is javascript
• Javascript is the future - especially with fast
browsers like Chrome
• Javascript is on the ugly side - braces and
brackets and semicolons lead to parse errors
Monday, January 24, 2011

3. CoffeeScript
• Cleans up Javascript
• Ruby-esque (designed to read like english)
and Python-esque (no ends, tab driven)
• Compiles to Javascript
Monday, January 24, 2011

4. Assignment
favorite_number = 314
is_a_programmer = true
# in javascript
var favorite_number = 314;
var is_a_programmer = true;
Monday, January 24, 2011

5. Conditions
if (favorite_number == 3.14)
is_a_programmer = true
else
is_a_programmer = false
alert(is_a_programmer)
# Conditions in javascript
if (favorite_number == 3.14) {
is_a_programmer = true;
} else {
is_a_programmer = false;
}
alert(is_a_programmer);
Monday, January 24, 2011

6. Functions
area_of_circle = (r) ->
3.14 * (r*r)
# in javascript
area_of_circle = function(r) {
return (3.14 * (r*r));
};
Monday, January 24, 2011

7. Other Stuff
• jQuery, Prototype, other frameworks - yes,
you can mix them in.
• Plugins - yes, you can mix them in.
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8. Installation
• 1) Install node.js
• 2) Install npm (node package manager)
• 3) Install coffeescript
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9. Install node.js
• mkdir ~/sources
• cd ~/sources
• wget http://nodejs.org/dist/node-v0.2.6.tar.gz
• sudo tar xvzf node[press tab]
• cd node[press tab]
• ./configure
• make
• sudo make install
Monday, January 24, 2011

10. Install npm
• cd ~/sources
• git clone http://github.com/isaacs/npm.git
• cd npm
• make
• sudo make install
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11. Install coffeescript
• sudo npm install coffee-script
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12. Try it out
• In terminal type: coffee
• You will get a command line interface
similar to irb.You can write coffee-script
directly from there if you wish.
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13. Using with Rails/Sinatra/etc
• Use the barista gem - https://github.com/Sutto/
barista
• Add it to your gemfile
• rails generate barista: install
• edit config/initializers/barista_config.rb as necessary
• Now your coffeescripts will automatically compile
to javascript
Monday, January 24, 2011

14. Good practices
• Create a app/javascripts folder
• Put all your coffeescript in that folder - app/javascripts/
application.coffee
• Set config/initializers/barista_config.rb to compile to
public/javascripts/compiled
• Now all your generated javascript from coffeescript will
be in a compiled folder and you can still use normal
javascript when necessary under your public/javascripts
folder
Monday, January 24, 2011

15. Conclusion
• CoffeeScript is a more enjoyable way to
write javascript
• You will make less errors writing javascript
with CoffeeScript
• You will probably write more powerful and
more organized code too
Monday, January 24, 2011