CoffeeScript

Obsah

Co to je?
Proč to používat?
Jak to vypadá?
Jak to rozchodit?

Co to je?

CoffeeScript is a little language that compiles
into JavaScript.

Co to je?

CoffeeScript is a little language that compiles
into JavaScript.

The code compiles one-to-one into the
equivalent JS, and there is no interpretation
at runtime.

JavaScript je v jádru docela dobrý jazyk, ale…


“ JavaScript had to look like Java only less so, be
Java’s dumb kid brother or boy-hostage sidekick.


“ JavaScript had to look like Java only less so, be
Java’s dumb kid brother or boy-hostage sidekick.

Plus, I had to be done in ten days or something
worse than JavaScript would have happened.
”
— Brendan Eich


Rychlejší vývoj


Rychlejší vývoj

Méně bugů


Rychlejší vývoj

Méně bugů

Lepší čitelnost

Jak to vypadá?

JavaScript CoffeeScript

Functions

var cube, square;
square = function(x) {
return x * x; square = (x) -> x * x
};
cube = function(x) { cube = (x) -> square(x) * x
return square(x) * x;
};


Objects

var kids = { kids =
brother: { brother:
name: "Max", name: "Max"
age: 11 age: 11
}, sister:
sister: { name: "Ida"
name: "Ida", age: 9
age: 9
}
};


If, Else, Conditional Assignment

var date, mood;
if (singing) { mood = greatlyImproved if singing
mood = greatlyImproved;
}
if (happy && knowsIt) { if happy and knowsIt
clapsHands(); clapsHands()
chaChaCha(); chaChaCha()
} else { else
showIt(); showIt()
}
date = friday ? sue : jill; date = if friday then sue else jill


OOP
var Animal, Horse, Snake, sam, tom;
var __hasProp = Object.prototype.hasOwnProperty, __extends =
class Animal
function(child, parent) { constructor: (@name) ->
for (var key in parent) {
if (__hasProp.call(parent, key)) child[key] = parent[key]; }
function ctor() { this.constructor = child; }
ctor.prototype = parent.prototype;
move: (meters) ->
child.prototype = new ctor; child.__super__ = parent.prototype; alert @name +" moved "+ meters +"m."
return child;};Animal = (function() {
function Animal(name) { this.name = name; }
Animal.prototype.move = function(meters) { class Snake extends Animal
return alert(this.name + " moved " + meters + "m.");
}; move: ->
return Animal;})();
Snake = (function() { __extends(Snake, Animal); function
alert "Slithering..."
Snake() { Snake.__super__.constructor.apply(this, arguments); super 5
} Snake.prototype.move = function() { alert("Slithering...");
return Snake.__super__.move.call(this, 5); }; return
Snake;})(); class Horse extends Animal
Horse = (function() { __extends(Horse, Animal); function
Horse() { move: ->
}
Horse.__super__.constructor.apply(this, arguments); alert "Galloping..."
Horse.prototype.move = function() { super 45
alert("Galloping..."); return
Horse.__super__.move.call(this, 45);
}; return Horse;})(); sam = new Snake "Sammy the Python"
sam = new Snake("Sammy the Python");
tom = new Horse("Tommy the Palomino"); tom = new Horse "Tommy the Palomino"


Loops

# Eat lunch.
for food in ['toast', 'cheese', 'wine']:
eat(food)

# Eat lunch.
eat food for food in ['toast', 'cheese', 'wine']

Loops

# Eat lunch.
for food in ['toast', 'cheese', 'wine']:
eat(food)

# Eat lunch.
eat food for food in ['toast', 'cheese', 'wine']

var food, _i, _len, _ref;
_ref = ['toast', 'cheese', 'wine'];
for (_i = 0, _len = _ref.length; _i < _len; _i++) {
food = _ref[_i];
eat(food);
}

Loops

for key in {‘foo’: ‘bar’}

for key, value in {‘foo’: ‘bar’}.items()

for key of {foo: ‘bar’}

for key, value of {foo: ‘bar’}

Ranges

for i in range(1, 10)

for i in range(10, 1, -1)

for i in range(1, 10, 2)

for i in [1..9] # nebo [1...10]

for i in [10..2]

for i in [1..9] by 2

Comprehensions

short_names = [name for name in list if len(name) < 5]

shortNames = (name for name in list when name.length < 5)

Slicing

my_list[3:6]

my_list[3:]

my_list[:-3]

myList[3..5]

myList[3..]

myList[...-3]

Slicing

my_list[3:6] = [1, 2, 3]

my_list[3:]

my_list[:-3]

myList[3..5] = [1, 2, 3]

myList[3..]

myList[...-3]

Splats
(a.k.a. argument list unpacking)

def foo(bar, *args): pass

foo = (bar, args...) ->

Chained Comparisons

cholesterol = 127

healthy = 200 > cholesterol > 60

The Existential Operator

alert "I knew it!" if elvis?

if (typeof elvis !== "undefined" && elvis !== null) {
alert("I knew it!");
}

Destructuring Assignment

theBait = 1000
theSwitch = 0

[theBait, theSwitch] = [theSwitch, theBait]

weatherReport = (location) ->
# Make an Ajax request to fetch the weather...
[location, 72, "Mostly Sunny"]

[city, temp, forecast] = weatherReport "Berkeley, CA"

Fat arrow – binding this

Account = (customer, cart) ->
@customer = customer
@cart = cart

$('.shopping_cart').bind 'click', (event) =>
@customer.purchase @cart

String Interpolation

author = "Wittgenstein"
quote = "A picture is a fact. -- #{author}"

sentence = "#{ 22 / 7 } is a decent approximation of π"

The CoffeeScript compiler is
itself written in CoffeeScript.

Node Package Manager
$ curl http://npmjs.org/install.sh | sh

$ npm install -g coffee-script

$ coffee --watch --compile *.coffee

19:45:31 - compiled myscript.coffee
In myscript.coffee, too many ) on line 39
In myscript.coffee, Parse error on line 3: Unexpected 'INDENT'

Odkazy
CoffeeScript homepage
http://jashkenas.github.com/coffee-script/

node.js
http://nodejs.org/

npm
http://npmjs.org/

Introduction to CoffeeScript
http://screencasts.org/episodes/introduction-to-coffeescript/

Js2Coffee – The JavaScript to CoffeeScript compiler.
http://ricostacruz.com/js2coffee/

CoffeeScript

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