Presented at RailsWayCon 2011

1. Raimonds Simanovskis
Rails-like JavaScript
using CoffeeScript,
Backbone.js and
Jasmine

2. Raimonds Simanovskis
github.com/rsim
@rsim
.com

3. The Problem

4. Ruby code in Rails

5. JavaScript code in
Rails 3.0.x

6. application.js
// Place your application-specific JavaScript functions and classes here
// This file is automatically included by javascript_include_tag :defaults

7. Which leads to...
(example from Redmine)

8. application.js
(example from Redmine)
/* redMine - project management software
Copyright (C) 2006-2008 Jean-Philippe Lang */
function checkAll (id, checked) {
var els = Element.descendants(id);
for (var i = 0; i < els.length; i++) {
if (els[i].disabled==false) {
els[i].checked = checked;
}
}
}
function toggleCheckboxesBySelector(selector) {
boxes = $$(selector);
var all_checked = true;
for (i = 0; i < boxes.length; i++) { if (boxes[i].checked == false) { all_checked = false; } }
for (i = 0; i < boxes.length; i++) { boxes[i].checked = !all_checked; }
}
function setCheckboxesBySelector(checked, selector) {
var boxes = $$(selector);
boxes.each(function(ele) {
ele.checked = checked;
});
}
function showAndScrollTo(id, focus) {
Element.show(id);
if (focus!=null) { Form.Element.focus(focus); }

9. /*
* 1 - registers a callback which copies the csrf token into the
* X-CSRF-Token header with each ajax request. Necessary to
application.js
* work with rails applications which have fixed
* CVE-2011-0447
* 2 - shows and hides ajax indicator
*/
Ajax.Responders.register({
(example from Redmine)
onCreate: function(request){
var csrf_meta_tag = $$('meta[name=csrf-token]')[0];
if (csrf_meta_tag) {
var header = 'X-CSRF-Token',
token = csrf_meta_tag.readAttribute('content');
if (!request.options.requestHeaders) {
request.options.requestHeaders = {};
}
request.options.requestHeaders[header] = token;
}
if ($('ajax-indicator') && Ajax.activeRequestCount > 0) {
Element.show('ajax-indicator');
}
},
onComplete: function(){
if ($('ajax-indicator') && Ajax.activeRequestCount == 0) {
Element.hide('ajax-indicator');
}
}
});
function hideOnLoad() {
$$('.hol').each(function(el) {
el.hide();
});
}
Event.observe(window, 'load', hideOnLoad);

10. The Problem #2

11. Do we really know
(and love?)
JavaScript?

12. Sample JavaScript
(from RailsCasts #267)
var CreditCard = {
cleanNumber: function(number) {
return number.replace(/[- ]/g, "");
},
validNumber: function(number) {
var total = 0;
number = this.cleanNumber(number);
for (var i=number.length-1; i >= 0; i--) {
var n = parseInt(number[i]);
if ((i+number.length) % 2 == 0) {
n = n*2 > 9 ? n*2 - 9 : n*2;
}
total += n;
};
return total % 10 == 0;
}
};
console.log(CreditCard.validNumber('4111 1111-11111111')); // true
console.log(CreditCard.validNumber('4111111111111121')); // false

13. We see as this
“ugly” Ruby
CreditCard = {
:cleanNumber => lambda { |number|
return number.gsub(/[- ]/, "");
},
:validNumber => lambda { |number|
total = 0;
number = CreditCard[:cleanNumber].call(number);
for i in 0..(number.length-1)
n = number[i].to_i;
if ((i+number.length) % 2 == 0)
n = n*2 > 9 ? n*2 - 9 : n*2;
end
total += n;
end;
return total % 10 == 0;
}
};
puts(CreditCard[:validNumber].call('4111 1111-11111111')); # true
puts(CreditCard[:validNumber].call('4111111111111121')); # false

14. Or as this “normal” Ruby
module CreditCard
def self.clean_number(number)
number.gsub(/[- ]/, "")
end
def self.valid_number?(number)
total = 0
number = clean_number(number)
for i in 0...number.length
n = number[i].to_i
if i+number.length % 2 == 0
n = n*2 > 9 ? n*2 - 9 : n*2
end
total += n
end
total % 10 == 0
end
end
puts CreditCard.valid_number?('4111 1111-11111111') # true
puts CreditCard.valid_number?('4111111111111121') # false

15. “Best practices” Ruby
class CreditCard
def initialize(number)
@number = clean_number(number)
end
def valid?
total = 0
for i in 0...@number.length
n = @number[i].to_i
if i+@number.length % 2 == 0
n = n*2 > 9 ? n*2 - 9 : n*2
end
total += n
end
total % 10 == 0
end
private
def clean_number(number)
number.gsub(/[- ]/, "")
end
end
puts CreditCard.new('4111 1111-11111111').valid? # true
puts CreditCard.new('4111111111111121').valid? # false

16. JavaScript has objects too!
var CreditCard = function(number) {
function cleanNumber(number) {
return number.replace(/[- ]/g, "");
}
this.number = cleanNumber(number);
};
CreditCard.prototype = {
isValid: function() {
var total = 0;
for (var i=this.number.length-1; i >= 0; i--) {
var n = parseInt(this.number[i]);
if ((i+this.number.length) % 2 == 0) {
n = n*2 > 9 ? n*2 - 9 : n*2;
}
total += n;
};
return total % 10 == 0;
}
};
console.log( (new CreditCard('4111 1111-11111111')).isValid() ); // true
console.log( (new CreditCard('4111111111111121')).isValid() ); // false

17. But this would be much
more Ruby-like!
class CreditCard
cleanNumber = (number) -> number.replace /[- ]/g, ""
constructor: (number) ->
@number = cleanNumber number
isValid: (number) ->
total = 0
for i in [0...@number.length]
n = +@number[i]
if (i+@number.length) % 2 == 0
n = if n*2 > 9 then n*2 - 9 else n*2
total += n
total % 10 == 0
console.log (new CreditCard '4111 1111-11111111').isValid() # true
console.log (new CreditCard '4111111111111121').isValid() # false

20. Sample CoffeeScript
# Assignment: # Splats:
number = 42 race = (winner, runners...) ->
opposite = true print winner, runners
# Conditions: # Existence:
number = -42 if opposite alert "I knew it!" if elvis?
# Functions: # Array comprehensions:
square = (x) -> x * x cubes = (math.cube num for num in list)
# Arrays:
list = [1, 2, 3, 4, 5]
# Objects:
math =
root: Math.sqrt
square: square
cube: (x) -> x * square x

21. Functions
square = (x) -> x * x
cube = (x) -> square(x) * x
fill = (container, liquid = "coffee") ->
"Filling the #{container} with #{liquid}..."
awardMedals = (first, second, others...) ->
gold = first
silver = second
rest = others
contenders = [
"Michael Phelps"
"Liu Xiang"
"Yao Ming"
"Allyson Felix"
"Shawn Johnson"
]
awardMedals contenders...

22. Objects and Arrays
song = ["do", "re", "mi", "fa", "so"]
singers = {Jagger: "Rock", Elvis: "Roll"}
bitlist = [
1, 0, 1
0, 0, 1
1, 1, 0
]
kids =
brother:
name: "Max"
age: 11
sister:
name: "Ida"
age: 9

23. Variable Scope
var changeNumbers, inner, outer;
outer = 1 outer = 1;
changeNumbers = -> changeNumbers = function() {
var inner;
inner = -1 inner = -1;
outer = 10 return outer = 10;
inner = changeNumbers() };
inner = changeNumbers();

24. Existential Operator
solipsism = true if mind? and not world?
speed ?= 75
footprints = yeti ? "bear"
zip = lottery.drawWinner?().address?.zipcode

25. Conditionals
mood = greatlyImproved if singing
if happy and knowsIt
clapsHands()
chaChaCha()
else
showIt()
date = if friday then sue else jill
options or= defaults

26. Loops
eat food for food in ['toast', 'cheese', 'wine']
countdown = (num for num in [10..1])
earsOld = max: 10, ida: 9, tim: 11
ages = for child, age of yearsOld
child + " is " + age

27. Classes, Inheritance
and super
class Animal
constructor: (@name) ->
move: (meters) ->
alert @name + " moved " + meters + "m."
class Snake extends Animal
move: ->
alert "Slithering..."
super 5
class Horse extends Animal
move: ->
alert "Galloping..."
super 45
sam = new Snake "Sammy the Python"
tom = new Horse "Tommy the Palomino"
sam.move()
tom.move()

28. Function Binding
Account = (customer, cart) ->
@customer = customer
@cart = cart
$('.shopping_cart').bind 'click', (event) =>
@customer.purchase @cart

29. And many other
nice features...

30. How to install?
brew install node # or install node.js otherwise
curl http://npmjs.org/install.sh | sh
npm install -g coffee-script

31. Back to the
Problem #1

32. Dynamic single page
application

33. Identifying
components
AppView

34. Identifying
components
AppView
TodoView
TodoView
TodoView

35. Identifying
components
AppView
keypress event
click event TodoView
dblclick event TodoView
TodoView
click event

36. Browser-side
Views and Models
AppView
TodoList
keypress event
click event TodoView Todo
dblclick event TodoView Todo
TodoView Todo
click event

37. Browser-side
Views and Models
AppView
new, fetch
TodoList
keypress event
click event TodoView create, save
Todo
dblclick event TodoView Todo
TodoView Todo
click event

38. Browser-side
Views and Models
AppView
refresh, add TodoList
keypress event
click event TodoView Todo
dblclick event TodoViewchange, destroy Todo
TodoView Todo
click event

39. Browser-side Models
and RESTful resources
Browser Rails
GET
TodoList TodosController
POST index
Todo PUT show
Todo create
DELETE update
Todo
destroy
JSON

41. Organize CoffeeScript
and JavaScript Code
using http://github.com/Sutto/barista

42. application.coffee
# main namespace
window.TodoApp = {}

43. Todo model
class TodoApp.Todo extends Backbone.Model
# If you don't provide a todo, one will be provided for you.
EMPTY: "empty todo..."
# Ensure that each todo created has `content`.
initialize: ->
unless @get "content"
@set content: @EMPTY
# Toggle the `done` state of this todo item.
toggle: ->
@save done: not @get "done"

44. TodoList collection
class TodoApp.TodoList extends Backbone.Collection
# Reference to this collection's model.
model: TodoApp.Todo
# Save all of the todo items under the `"todos"` namespace.
url: '/todos'
# Filter down the list of all todo items that are finished.
done: ->
@filter (todo) -> todo.get 'done'
# Filter down the list to only todo items that are still not finished.
remaining: ->
@without this.done()...
# We keep the Todos in sequential order, despite being saved by unordered
# GUID in the database. This generates the next order number for new items.
nextOrder: ->
if @length then @last().get('order') + 1 else 1
# Todos are sorted by their original insertion order.
comparator: (todo) ->
todo.get 'order'

45. Todo item view
class TodoApp.TodoView extends Backbone.View
# ... is a list tag.
tagName: "li"
# Cache the template function for a single item.
template: TodoApp.template '#item-template'
# The DOM events specific to an item.
events:
"click .check" : "toggleDone"
"dblclick div.todo-content" : "edit"
"click span.todo-destroy" : "destroy"
"keypress .todo-input" : "updateOnEnter"
# The TodoView listens for changes to its model, re-rendering. Since there's
# a one-to-one correspondence between a **Todo** and a **TodoView** in this
# app, we set a direct reference on the model for convenience.
initialize: ->
_.bindAll this, 'render', 'close'
@model.bind 'change', @render
@model.bind 'destroy', => @remove()
# Re-render the contents of the todo item.
render: ->
$(@el).html @template @model.toJSON()
@setContent()
this

46. # Re-render the contents of the todo item.
render: ->
$(@el).html @template @model.toJSON()
@setContent()
Todo item view
this
# To avoid XSS (not that it would be harmful in this particular app),
# we use `jQuery.text` to set the contents of the todo item.
setContent: ->
content = @model.get 'content'
@$('.todo-content').text content
@input = @$('.todo-input')
@input.blur @close
@input.val content
# Toggle the `"done"` state of the model.
toggleDone: ->
@model.toggle()
# Switch this view into `"editing"` mode, displaying the input field.
edit: ->
$(@el).addClass "editing"
@input.focus()
# Close the `"editing"` mode, saving changes to the todo.
close: ->
@model.save content: @input.val()
$(@el).removeClass "editing"
# If you hit `enter`, we're through editing the item.
updateOnEnter: (e) ->
@close() if e.keyCode == 13
# Destroy the model.
destroy: ->
@model.destroy()

47. Application view
class TodoApp.AppView extends Backbone.View
# Instead of generating a new element, bind to the existing skeleton of
# the App already present in the HTML.
el: "#todoapp"
# Our template for the line of statistics at the bottom of the app.
statsTemplate: TodoApp.template '#stats-template'
# Delegated events for creating new items, and clearing completed ones.
events:
"keypress #new-todo" : "createOnEnter"
"keyup #new-todo" : "showTooltip"
"click .todo-clear a" : "clearCompleted"
# At initialization we bind to the relevant events on the `Todos`
# collection, when items are added or changed. Kick things off by
# loading any preexisting todos that might be saved.
initialize: ->
_.bindAll this, 'addOne', 'addAll', 'renderStats'
@input = @$("#new-todo")
@collection.bind 'add', @addOne
@collection.bind 'refresh', @addAll
@collection.bind 'all', @renderStats
@collection.fetch()

48. @collection.bind 'add', @addOne
@collection.bind 'refresh', @addAll
@collection.bind 'all', @renderStats
Application view
@collection.fetch()
# Re-rendering the App just means refreshing the statistics -- the rest
# of the app doesn't change.
renderStats: ->
@$('#todo-stats').html @statsTemplate
total: @collection.length
done: @collection.done().length
remaining: @collection.remaining().length
# Add a single todo item to the list by creating a view for it, and
# appending its element to the `<ul>`.
addOne: (todo) ->
view = new TodoApp.TodoView model: todo
@$("#todo-list").append view.render().el
# Add all items in the collection at once.
addAll: ->
@collection.each @addOne
# Generate the attributes for a new Todo item.
newAttributes: ->
content: @input.val()
order: @collection.nextOrder()
done: false
# If you hit return in the main input field, create new **Todo** model,
# persisting it to server.
createOnEnter: (e) ->
if e.keyCode == 13
@collection.create @newAttributes()
@input.val ''

49. view = new TodoApp.TodoView model: todo
@$("#todo-list").append view.render().el
# Add all items in the collection at once.
Application view
addAll: ->
@collection.each @addOne
# Generate the attributes for a new Todo item.
newAttributes: ->
content: @input.val()
order: @collection.nextOrder()
done: false
# If you hit return in the main input field, create new **Todo** model,
# persisting it to server.
createOnEnter: (e) ->
if e.keyCode == 13
@collection.create @newAttributes()
@input.val ''
# Clear all done todo items, destroying their views and models.
clearCompleted: ->
todo.destroy() for todo in @collection.done()
false
# Lazily show the tooltip that tells you to press `enter` to save
# a new todo item, after one second.
showTooltip: (e) ->
tooltip = @$(".ui-tooltip-top")
val = @input.val()
tooltip.fadeOut()
clearTimeout @tooltipTimeout if @tooltipTimeout
unless val == '' or val == @input.attr 'placeholder'
@tooltipTimeout = _.delay ->
tooltip.show().fadeIn()
, 1000

50. #todoapp
index.html.haml
.title
%h1 Todos
.content
#create-todo
%input#new-todo{:placeholder => "What needs to be done?", :type => "text"}/
%span.ui-tooltip-top{:style => "display:none;"} Press Enter to save this task
#todos
%ul#todo-list
#todo-stats
%ul#instructions
%li Double-click to edit a todo.
:coffeescript
$ ->
TodoApp.appView = new TodoApp.AppView collection: new TodoApp.TodoList
%script#item-template{:type => "text/html"}
.todo{:class => "{{#done}}done{{/done}}"}
.display
%input{:class => "check", :type => "checkbox", :"{{#done}}checked{{/done}}" => true}
.todo-content
%span.todo-destroy
.edit
%input.todo-input{:type => "text", :value => ""}
%script#stats-template{:type => "text/html"}
{{#if total}}
%span.todo-count

51. %input#new-todo{:placeholder => "What needs to be done?", :type => "text"}/
%span.ui-tooltip-top{:style => "display:none;"} Press Enter to save this task
#todos
%ul#todo-list
index.html.haml
#todo-stats
%ul#instructions
%li Double-click to edit a todo.
:coffeescript
$ ->
TodoApp.appView = new TodoApp.AppView collection: new TodoApp.TodoList
%script#item-template{:type => "text/html"}
.todo{:class => "{{#done}}done{{/done}}"}
.display
%input{:class => "check", :type => "checkbox", :"{{#done}}checked{{/done}}" => true}
.todo-content
%span.todo-destroy
.edit
%input.todo-input{:type => "text", :value => ""}
%script#stats-template{:type => "text/html"}
{{#if total}}
%span.todo-count
%span.number {{remaining}}
%span.word {{pluralize remaining "item"}}
left.
{{/if}}
{{#if done}}
%span.todo-clear
%a{:href => "#"}
Clear
%span.number-done {{done}}
completed
%span.word-done {{pluralize done "item"}}
{{/if}}

52. One more thing:
Backbone Controllers
Routers
class Workspace extends Backbone.Controller Router
routes:
"help" : "help" #help
"search/:query" : "search" #search/kiwis
"search/:query/p:page": "search" #search/kiwis/p7
help: ->
...
search: (query, page) ->
...

53. How do you test it?

54. RSpec-like testing for
JavaScript

55. Together with all
other tests

56. Testing Todo model
describe "Todo", ->
todo = null
ajaxCall = (param) -> jQuery.ajax.mostRecentCall.args[0][param]
beforeEach ->
todo = new TodoApp.Todo
todos = new TodoApp.TodoList [todo]
it "should initialize with empty content", ->
expect(todo.get "content").toEqual "empty todo..."
it "should initialize as not done", ->
expect(todo.get "done").toBeFalsy()
it "should save after toggle", ->
spyOn jQuery, "ajax"
todo.toggle()
expect(ajaxCall "url").toEqual "/todos"
expect(todo.get "done").toBeTruthy()

57. and TodoList
collection
describe "TodoList", ->
attributes = [
content: "First"
done: true
,
content: "Second"
]
todos = null
beforeEach ->
todos = new TodoApp.TodoList attributes
it "should return done todos", ->
expect(_.invoke todos.done(), "toJSON").toEqual [attributes[0]]
it "should return remaining todos", ->
expect(_.invoke todos.remaining(), "toJSON").toEqual [attributes[1]]

58. Rails 3.1
Asset Pipeline

59. application.js.coffee
using Sprockets
#= require jquery
#= require underscore
#= require backbone
#= require handlebars
#= require ./todo_app
#= require_tree ./models
#= require ./views/helpers
#= require_tree ./views

60. Watch RailsConf
DHH keynote
http://en.oreilly.com/rails2011/public/schedule/detail/19068

61. References
http://jashkenas.github.com/coffee-script/
http://documentcloud.github.com/backbone/
http://pivotal.github.com/jasmine/
https://github.com/rsim/backbone_coffeescript_demo

62. Used in eazybi.com