Resumen express de coffeescript

# single line comment

###
 multiline comment, perhaps a LICENSE.
###

# All variables are by default scoped locally
 my_var = "Hello world"
 pi = 3.1416

# Attach a variable to the global or window object to make it global
 window.my_var = "Hello world"

# use the slim arrow to declare a function
func = -> "bar"

sumXtoTen = (x) ->
 10 + x

# arguments are specified in parenthesis before the arrow
times = (a, b) -> a * b

# you can specify default arguments
times = (a = 10, b = 15) -> a * b

# use splats to receive N arguments via an array
sum = (nums...) ->
 result = 0
 nums.reduce (total, num) -> total + num

# you can avoid parethesis in function calls with at least 1 argument
alert "hello world"
console.log "this is the end"

# on the contrary you cannot call a function without parenthesis and zero
# arguments

# this fails
alert
# this is O.K.
alert()

# use the fat arrow to bound a function call to the local context
# mostly used in callbacks
# avoid using the conventional self = this is not very coffeescriptish

this.clickHandler = -> alert "clicked"
element.addEventListener "click", (e) => this.clickHandler(e)

# Object literals

 # regular Javascript syntaxis
 object1 = {one: 1, two: 2}

 # without braces
 object2 = one: 1, two: 2

 # using new lines instead of commands
 object3 =
 one: 1
 two: 2

# Arrays

 # avoid the trailing comma
 array1 = [1, 2, 3]

 # using new lines
 array2 = [
 1
 2
 3
 ]

# ruby style one liners if and unless
alert("Hello world") if sayHi is yes
alert("Hello world") unless sayHi isnt yes

# one liner if then or ternary
if true isnt true then "Panic"
if true isnt true then "Panic" else "Everything just works!"

# use plain old english for not, is, isnt, and, or
if not true then "Panic"
if true is true then "Everything's gonna be allright"
if true isnt true then "We'll burn in hell!!"
if total is 0 and discount is 0 then "God save us all!"

# oh good old ruby and multiline strings also!
 favoriteColor = "Blue. No, yel..."
 question = "Bridgekeeper: What... is your favorite color?
 Galahad: #{favoriteColor}
 Bridgekeeper: Wrong!
 "

# Iterate over the array's elements
for name in ["Roger", "Roderick"]
 alert "Release #{name}"

# using index
for name, i in ["Roger", "Roderick"]
 alert "#{i} - Release #{name}"

# one liner
release prisioner for prisioner in ["Roger", "Roderick"]

# use keyword when to filter or select
release prisioner for prisioner in ["Roger", "Roderick"] when prisioner[0] is "R"

# use comprehensions to iterate over an object's properties
names = sam: seaborn, donna: moss
alert("#{first} #{last}") for first, last of names

# use low leve while be aware that it returns an array of results like a map
num = 6
minstrel = while num -= 1
 num + " Brave Sir Robin ran away"

# slicing an array/ string with ranges
firstTwo = ["one", "two", "three"][0..1]
my = "my string"[0..1]

# includes or checking existence
words = ["rattled", "roudy", "rebbles", "ranks"]
alert "Stop wagging me" if "ranks" in words

# a map
names = (muppet.name for muppet in muppets)

# a filter or select
names = (muppe.name for muppet in muppets when muppet.name isnt "peggy")

# property iteration over an object
object = {one: 1, two: 2}
alert("#{key} = #{value}") for key, value of object

# @ is an alias for this
 this.saviour = true
 @saviour = true

# :: is an alias for prototype
 User.prototype.first = -> @records[0]
 User::first = -> @records[0]

# the ? symbols returns true unless null or undefined
 praise if brian?

# use ? in place of || operator
 velocity = souther ? 40

# use ? before accessing a property, similar to Active Support's try method
blacknight.getLegs()?.kick()

# check if a property is a function and callable
blacknight.getLegs().kick?()

# use it for initialization
hash ?= {}

# Modules: you can create modules using the do notation
FormHelpers = do ->
 # Public methods
 textFieldTag: () ->
 selectTag: () ->
 labelTag: () ->

 # Private methods
 _initTextField = () ->
 _buildLabelTag = () ->

# basic class structure
class Animal
 # constant
 @BASE_PRICE: 100.00

 # basic initializer or constructur
 constructor: (args = {}) ->
 # instance variables
 @name = args.name
 @species = args.species

 # instance method
 sell: (customer) ->
 # accessing constant
 @constructor.BASE_PRICE

 # class method
 @find: (name) ->

# use fat arrow in callbacks to keep the right context
class Animal
 price: 5

 sell: =>
 alert "Give me #{@price} shillings!"

animal = new Animal
$("#sell").click(animal.sell)

# Inheritance and Super

# use extends to inherit all the instance properties
class Animal
 constructor: (@name) ->

 alive: ->
 false

class Parrot extends Animal
 constructor: ->
 # use super to call the parents method
 super("Parrot")

 dead: ->
 not @alive()

# Mixins to share common behavior or roles
# there's no native support in coffee but you can implement it

extend = (obj, mixin) ->
 obj[name] = method for name, method of mixin
 obj

include = (klass, mixin) ->
 extend klass.prototype, mixin

# usage
include Parrot,
 isDeceased: true

(new Parrot).isDeceased

###
This approach can be useful if you have a simple touch of js in your apps and still keeping your code decoupled
lets say, using jquery, some plugins, animations, effects
###

###
First: Create namespaces and containers for your view modules
app/assets/my_app.coffee
###
window.MyApp = 
 ViewHelpers:
 Orders: {}
 Customers: {}
 Shared: {}

###
Second: For each html view with specific js behaviour create a my_view_name.coffee file
and use the Module pattern
app/assets/my_app/view_helpers/orders/index.coffee
###

MyApp.ViewHelpers.Orders.Index = do ->
 # Private interface
 # Place helper methods only called from inside the module
 _sayHi = (name) ->
 alert(name)

 # Public interface
 # Place here methods that should be called from the outside 
 init: ->
 _sayHi("Mr. Satan")

### 
Third: Fire the desired behaviour in your view after the dom is ready
app/views/orders/index.html.erb
###

<% content_for :local_js %>
<script>
 $(function(){
 MyApp.ViewHelpers.Orders.Index.init();
 });
</script>
<% end %>

###
Finally: Include the my_app.coffee file in your application.coffee
app/assets/application.coffee
###
#=require my_app.coffee

###
First: Define an MV structure for your javascript code under
app/assets/javascripts
###

your_app_name/
 models/
 views/
 utils/
 your_app_name.coffee

###
Second: Define global variables/namespaces to load each object type
inside my_appname.coffee
###

#=require_self
#=require jquery
#=require knockout
#=require_tree

window.YourAppName:
 Models: {}
 Views:
 Users: {}
 Posts: {}
 Utils: {}

###
Third: Place every model, view or utility class in their folder
use class YourAppName.Models.User, class YourAppName.Views.Users.Create
pattern to defined each class name and keeping them under their scopes
###

class YourAppName.Models.User
 constructor: (args = {}) ->

class YourAppName.Views.Users.Show
 constructor: ->

# Fourth: Create objects and apply knockout bindings (or any other binding library) in the views show.html.erb

<!-- ko with: user --!>
 <span data-bind="text: firstName"></span>
 <span data-bind="text: lastName"></span>
<!-- /ko --!>

<script>
 ko.applyBindings(new YourAppName.Views.Users.Show());
</script>

# Fifth and last, require your_appname.coffee script inside your rails application.js
#=require your_app_name