Damn Fine CoffeeScript

Some Kind of Holy
Python

Ruby

JavaScrip t

Raw
var render = function (width, height, draw, filePath)
{
var canvas = new Canvas(width, height),
ctx = canvas.getContext('2d');
draw.call(ctx);
var out = fs.createWriteStream(filePath),
stream = canvas.createPNGStream();
stream.on('data', function(chunk) {
out.write(chunk);
});
stream.on('end', function() {
console.log("Created: " + filePath);
});
};

Brewed

render = (width, height, draw, filePath) ->
canvas = new Canvas(width, height)
draw.call canvas.getContext '2d'
out = fs.createWriteStream filePath
stream = canvas.createPNGStream()
stream.on 'data', (chunk) ->
out.write chunk
stream.on 'end', ->
console.log "Created: #{filePath}"

Basically

● function is () ->
● local variables

● indentation

● omittable parentheses

True To JavaScript

The golden rule of CoffeeScript is: "It's just
JavaScript"

Less Syntactic Noise

stream.on('end', function() {
console.log("Created: " +
filePath);
});

stream.on 'end', ->
console.log "Created: #{filePath}"

My perspective

Node

A platform: JS machine + CommonJS stdlib

Browser

Just JS (generated)

Convert & Eval...

<script src="/extras/coffee-script.js"></script>
<script type="text/coffeescript">
# coffee time
</script>

Node

$ npm install coffee-script

101

# Assignment:
number = 42
opposite = true

Conditions

if happy and knowsIt
clapsHands()
chaChaCha()
else
showIt()

date = if friday then sue else jill

options or= defaults

number = -42 if opposite

Functions

square = (x) -> x * x

cube = (x) -> square(x) * x

fill = (container, liquid="coffee") ->
"Filling the #{container} with #{liquid}..."

noop = ->

In JQuery

$('span').each ->
it = $(this)
if it.is('.style-1, .style-20') or
not it.attr('class')
it.replaceWith(it.html())

Data

# Arrays:
list = [1, 2, 3, 4, 5]

# Objects:
math =
root: Math.sqrt
square: square
cube: (x) -> x * square x

modes = {ready: yes, balance: off}

bitlist = [
1, 0, 1
0, 0, 1
1, 1, 0
]

Compile

$ coffee -c some.coffee

# or just print out
$ coffee -p some.coffee

number = 42
opposite = true

number = -42 if opposite

list = [1, 2, 3, 4, 5]

math =
root: Math.sqrt
square: square
cube: (x) -> x * square x

var list, math, number, opposite;
number = 42;
opposite = true;
if (opposite) {
number = -42;
}
list = [1, 2, 3, 4, 5];
math = {
root: Math.sqrt,
square: square,
cube: function(x) {
return x * square(x);
}
};

Lexical Scopes & Safety

outer = 1
changeNumbers = ->
inner = -1
outer = 10
inner = changeNumbers()

var changeNumbers, inner, outer;
outer = 1;
changeNumbers = function() {
var inner;
inner = -1;
return outer = 10;
};
inner = changeNumbers();

Syntactic

Thin Coat of Sugar

And Some Boilerplate

Sugar++

# Splats:
race = (winner, runners...) ->
print winner, runners

# Existence:
alert "I knew it!" if elvis?

var race;
var __slice = Array.prototype.slice;
var race = function() {
var runners, winner;
winner = arguments[0], runners = 2 <= arguments.length ?
__slice.call(arguments, 1) : [];
return print(winner, runners);
};
if (typeof elvis !== "undefined" && elvis !== null) {
alert("I knew it!");
}

Expressions, Implicitness, Return

Unpacking

[first, second] = [1, 2, 3, 4]

_ref = [1, 2, 3], first = _ref[0], second = _ref[1];

{puts, inspect} = require 'util'

_ref2 = require('util'), puts = _ref2.puts, inspect =
_ref2.inspect;

Comprehensions!

cubes = (math.cube num for num in list)

var cubes;
cubes = (function() {
var _i, _len, _results;
_results = [];
for (_i = 0, _len = list.length; _i < _len; _i++) {
num = list[_i];
_results.push(math.cube(num));
}
return _results;
})();

Comprehensive

yearsOld = max: 10, ida: 9, tim: 11

ages = for child, age of yearsOld
child + " is " + age

Closing Over Loops

for filename in list
do (filename) ->
fs.readFile filename, (err, contents) ->
compile filename, contents.toString()

Operator Names
CoffeeScript JavaScript

is, isnt ===, !==

and, or, not &&, ||, !

true, yes, on true

false, no, off false

in, of in, N/A

@, this this

:: prototype

Different Kinds of Else

● unless
● a?

●a ? b

● a ?= b

● a?.b

Classes
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()

var Animal, Horse, Snake, sam, tom;
var __hasProp = Object.prototype.hasOwnProperty, __extends =
function(child, parent) {
for (var key in parent) { if (__hasProp.call(parent, key))
child[key] = parent[key]; }
function ctor() { this.constructor = child; }
ctor.prototype = parent.prototype;
child.prototype = new ctor;
child.__super__ = parent.prototype;
return child;
};

Animal = (function() {
function Animal(name) {
this.name = name;
}
Animal.prototype.move = function(meters) {
return alert(this.name + " moved " + meters + "m.");
};
return Animal;
})();

Snake = (function() {
__extends(Snake, Animal);
function Snake() {
Snake.__super__.constructor.apply(this, arguments);
}
Snake.prototype.move = function() {
alert("Slithering...");
return Snake.__super__.move.call(this, 5);
};
return Snake;
})();

Binding => This

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

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

var Account;
var __bind = function(fn, me){ return function(){ return
fn.apply(me, arguments); }; };
Account = function(customer, cart) {
this.customer = customer;
this.cart = cart;
return $('.shopping_cart').bind('click', __bind(function(event)
{
return this.customer.purchase(this.cart);
}, this));
};

● Literals: Functions, Objects and Arrays
● If, Else, Unless, and Conditional Assignment

● Splats...
● Array Slicing and Splicing

● Loops and Comprehensions

● Destructuring Assignment

● Everything is an Expression

● Operators and Aliases
● Lexical Scoping and Variable Safety

● Classes, Inheritance, and Super

● Function Binding

● Switch and Try/Catch
● Chained Comparisons

● String Interpolation, Heredocs, and Block

Comments
● Extended Regular Expressions

● Embedded JavaScript

Coding in Coffee

sameness?

seeing clearly..

transparencies..

choices...

Tinkering Fun!

Node goodies: Zombie.js, Canvas, ...

$ npm link .

$ coffee --watch src

$ cake

Cakefile
{spawn, exec} = require 'child_process'

SRC = 'js/src'
LIB = 'js/lib'

task 'build', "compile coffee to js", -> build onErrorExit

task 'watch', "continously compile coffee to js", ->
cmd = spawn "coffee", ["-cw", "-o", LIB, SRC]
cmd.stdout.on "data", (data)-> process.stdout.write data
cmd.on "error", onErrorExit

build = (cb)->
console.log "Coffee compiling..."
exec "rm -rf #{LIB} && coffee -c -l -b -o #{LIB} #{SRC}",
(err, out)-> cb err

onErrorExit = (err)->
if err
process.stdout.write "#{err.stack}n"
process.exit -1

Image Tributes (CC)

"Black as midnight on a moonless night."
Knight of the Holy Grail
Reflecting on a Sunday afternoon
In The Red Room
Fall down mountains, just don't fall on me
Midnight Black
Orrery Steam Punk Assemblage by urbandon
Steampunk Time Contraption

Damn Fine CoffeeScript

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