Presentation on CoffeeScript programming language.

1. Script
by
Scott Leberknight

2. Created by Jeremy Ashkenas
https://github.com/jashkenas/coffee-script
Compiles to JavaScript

3. "It's just JavaScript"

6. var cube, cubes, num;
cube = function(x) {
return Math.pow(x, 3);
};
cubes = (function() {
var _i, _len, _ref, _results;
_ref = [1, 2, 3, 4, 5];
_results = [];
for (_i = 0, _len = _ref.length; _i < _len; _i++) {
num = _ref[_i];
_results.push(cube(num));
}
return _results;
})();
console.log(cubes);
JavaScript

7. cube = (x) -> x * x * x
cubes = (cube num for num in [1, 2, 3, 4, 5])
console.log cubes

8. Let's Get Started..

9. OS X
Install Homebrew
brew install node
curl http://npmjs.org/install.sh | sh
npm install coffee-script
coffee -v
http://mxcl.github.com/homebrew/

10. Linux*
install node and npm
(http://joyeur.com/2010/12/10/installing-node-and-npm/ )
npm install coffee-script
coffee -v
(* Windoze people can uze these instructions on Cygwin)

11. Drinking some Coffee..

12. ⌘-R

13. ⌘-B

14. $ coffee -c my.coffee
$ node my.js
[ 2048, 4096, 6144, 8192, 10240 ]

15. $ coffee
coffee> nums = (x * 1024 for x in [2..10] by 2)
2048,4096,6144,8192,10240
coffee> typeof(nums)
object
coffee> nums.length
5
coffee> nums[4]
10240
coffee> quit()

16. $ coffee --watch my.coffee
[ 2048, 4096, 6144, 8192, 10240 ]
[ 1024, 2048, 3072, 4096, 5120 ]

18. <script type="text/coffeescript">
nums = (x * 1024 for x in [2..10] by 2)
console.log nums
</script>

19. Everything's an expression
result = if (2 > 1) then "Yep" else "Hmmmm..."
console.log result
=> Yep

20. Look Ma! No var needed

21. book = "I Am America (And So Can You!)"
var book;
book = "I Am America (And So Can You!)";
JavaScript
http://www.amazon.com/Am-America-So-Can-You/dp/0446580503

22. Significant Whitespace
if isFood(animal)
strangle()
eat()
else
slitherAlong()22

23. Significant Whitespace
if isFood(animal)
strangle()
eat()
else
slitherAlong() 23

24. Functions.. the basics

25. noop = ->
-> 'The answer is 42'
console.log do -> 'What is the question?'
answerer -> 'The answer is 42'
mult = (x, y) -> x * y

26. mult = (x, y) -> x * y
var mult;
mult = function(x, y) {
JavaScript
return x * y;
};

27. console.log do -> 'What is the question?'
console.log((function() {
return 'What is the question?';
})());
JavaScript

28. Arrays & Objects

29. a = [1, 2, 3, 4, 5]
a[1..2] # inclusive range: [2, 3]
a[1...2] # exclusive range: [2]
a[0..-1] # [1, 2, 3, 4, 5]
a[2..-2] # [3, 4]

30. range = [1..10]
range = [1..21]
range = [1..22] # Inflection pt! (*)
range = [1..100]
range = [1..100000]
(* in version 1.0.1 )

31. fellowship =
wizard: 'Gandalf'
hobbits: ['Frodo', 'Pippin', 'Sam']

32. delta = 'u0394'
greekUnicode = { delta }
var delta, greekUnicode;
delta = 'u0394';
greekUnicode = {
JavaScript
delta: delta
};

33. Operators & Aliases

34. CoffeeScript JavaScript
==, is ===
!=, isnt !===
and &&
or ||
of in
in (no equivalent)
@, this this
true, yes, on true
false, no, off false

35. goodStudent = yes if grade in ['A', 'B']
stop() unless greenLight is on
if (book is "1984")
removeFromAllKindles()

36. Existential operator
believer = if aliens? then yes else no
console.log "I Believe" if believer
options ?= {}
options or= defaults
customer?.contactInfo?.emailAddress

37. Getting Loopy

38. Iterating Arrays using "in"
a = [1, 2, 3, 4, 5]
for val in a
doSomethingWith(val)

39. Loops return a value
a = [1, 2, 3, 4, 5]
timesTwo = for val in a
val * 2
=> [2, 4, 6, 8, 10 ]

40. Loops do not create scope..
countdown = [10..0]
for num in countdown
break if errorDetected()
if num is 0
console.log 'Blast-off!'
else
console.log "Aborted with #{num} seconds left!"

41. Iterating objects using "of"
for prop, val of someObject
# do something...

42. Iterating objects with "for
own" (hasOwnProperty)
Human = ->
Human::species = 'Homo-Sapiens'
ceo = new Human()
ceo.name = "Chris D'Agostino"
ceo.company = 'Near Infinity'
ceo.yearFounded = 2002
for own prop, val of ceo
console.log "#{prop} = #{val}"

43. What do vampires do while it's
dark?

44. while isDarkOutside()
suckBlood()

45. . .or until it's day time?

46. until isDayTime()
suckBlood()

47. ¿Comprendo?

48. Array Comprehensions
foods = ['pizza', 'soda', 'beer']
consume food for food in foods
consume food if food is 'beer' for food in foods
consume food for food in foods when food is 'beer'

49. nums = [1..10]
doubles = (n * 2 for n in nums)
squares = (n * n for n in nums)
evens = (n for n in nums when n % 2 is 0)
evensSquared = (n * n for n in evens)

50. Ripping things apart..
(a.k.a. de-structuring assignment)

51. [a, b] = [b, a]

52. [firstName, mi, lastName] = ['Wile', 'E', 'Coyote']

53. weatherReport = (location) ->
# Get the weather for real...
[location, 70, "Partly Cloudy"]
[city, temp, forecast] = weatherReport "Reston, VA"

54. fellowship =
maiar: ['Gandalf']
hobbits: ['Frodo', 'Sam', 'Merry', 'Pippin']
elves: ['Legolas']
dwarves: ['Gimli']
men: ['Aragorn', 'Boromir']
{hobbits: theHobbits, men: theMen} = fellowship
# or simply...
{hobbits, men} = fellowship

55. [sauce, toppings..., crust] = ['meat', 'pepperoni', 'banana
peppers', 'green peppers', 'thin']
console.log "Your pizza is a #{crust} crust with #{sauce}
sauce and #{toppings.join(', ')} on top"
spl at!
55

56. Functions.. the Good Stuff

57. Functions are bound or unbound
Functions create scope
Variable declarations are pushed to the top of the
closest scope
Variables are not visible outside declared scope

58. weirdAl = function() {
a = a + 1;
// What's a's value at this point?
var a = 10;
return a;
}
result = weirdAl();
JavaScript

59. Scoping..
outer = 1 var changeNumbers, inner, outer;
changeNumbers = -> outer = 1;
inner = -1 changeNumbers = function() {
outer = 10 var inner;
inner = -1;
inner = changeNumbers()
return outer = 10;
};
inner = changeNumbers();
JavaScript
Example from: http://jashkenas.github.com/coffee-script/

60. Context is key.. but what is
this?

61. @ is this, this is @

62. Bound function
setAnswer = (answer) -> @answer = answer
deepThought = {}
deepThought.setAnswer = setAnswer
deepThought.setAnswer 42
console.log deepThought.answer
=> 42

63. Applying context..
setAnswer = (answer) -> @answer = answer
deepThought = {}
setAnswer.apply deepThought, [ 42 ]
console.log deepThought.answer
=> 42

64. Context via new..
Computer = (answer) ->
@answer = answer
deepThought = new Computer(42)
watson = new Computer("What is Toronto?")
console.log deepThought.answer
=> 42
console.log watson.answer
=> "What is Toronto?"

65. Capturing this..
callback = (message) => @voicemail.push message
=> binds a function to the current scope

66. default arguments
selectMeals = (breakfast = 'Chick Fil A',
lunch = 'Macaroni Grill', dinner = 'Thai Noy') ->
"You chose #{breakfast}, #{lunch}, and #{dinner}"
console.log selectMeals("McDonald's", 'Subway', 'Outback')
=> You chose McDonald's, Subway, and Outback
console.log selectMeals(null, 'Subway', null)
=> You chose Chick Fil A, Subway, and Thai Noy
console.log selectMeals(null, null, null)
=> You chose Chick Fil A, Macaroni Grill, and Thai Noy

67. pizza = (sauce = 'tomato', toppings..., crust) ->
"A #{crust} pizza with #{sauce} sauce #{listOf(toppings)}"
console.log pizza('white', 'thin crust')
console.log pizza('tomato', 'pepperoni', 'pan')
console.log pizza(null, 'pepperoni', 'peppers', 'thin crust')
67

68. Class-based OO

69. Prototypal inheritance
var Animal = function(name, species) {
this.name = name;
this.species = species;
}
Animal.prototype.eat = function(food) { ... }
Animal.prototype.sleep = function() { ... }
Animal.prototype.play = function() { ... }
var felix = new Animal('Felix', 'Feline');
felix.sleep();
var fido = new Animal('Fido', 'Canine');
fido.play();
fido.eat();
JavaScript

70. class Bike
constructor: (@brand) ->
@gear = 1
changeGear: (newGear) ->
@gear = newGear
currentGear: ->
@gear
status: ->
"#{@brand} cruising in gear #{@gear}"

71. class MtnBike extends Bike
changeGear: (newGear) ->
# do something special for mtn bikes...
super newGear
cruiser = new Bike("Schwinn")
cruiser.changeGear(4)
console.log cruiser.status()
mtn = new MtnBike("Specialized")
mtn.changeGear(8)
console.log mtn.status()

72. Grab-Bag..

73. string interpolation
embedded JS using `...` (backticks)
switch/when/else
try/catch/finally
multi-line strings
enhanced regular expressions
Cake and Cakefiles

74. Other Considerations..
Debugging
Compilation
Deployment
Testing

75. Let's Review..

76. "It's just JavaScript"

77. "Because DHH says so..."
(yes, this is a joke)

78. Refs

79. CoffeeScript: Accelerated JavaScript Development
http://pragprog.com/titles/tbcoffee/coffeescript
CoffeeScript GitHub page
http://jashkenas.github.com/coffee-script/

80. http://lmgtfy.com/?q=coffeescript

81. photo attributions
Coffee # 1 -
http://www.flickr.com/photos/dyobmit/18588671/
Coffee # 2 -
http://www.flickr.com/photos/ibcbulk/86885289/
Python -
http://www.flickr.com/photos/lesmontsdore/5513104816/
Rip Apart Napkin -
http://www.flickr.com/photos/benreichelt/5543115344/
Weird Al - http://www.flickr.com/photos/schilder/4749864091/
Splat Wallpaper -
http://wallpaperstock.net/digital-splat_wallpapers_11732_1600x1200_1.html
Grab Bag -
http://www.flickr.com/photos/maynard/2126229821/
(others from iStockPhoto...)

82. (my info)
scott.leberknight@nearinfinity.com
www.nearinfinity.com/blogs/
twitter: sleberknight