CoffeeScript: A New Brew

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CoffeeScript A New Brew David L Kinney WindyCityRails Chicago 2011

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My History with JS

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS 1995 JS released It’s not Applets! YAY! 1996–2003 DHTML fails Meh. 2004–2009 GMail, Google Maps, jQuery Ajax! YAY! Present MVC in the browser Meh.

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My History with JS Today, I love JavaScript

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My History with JS Today, I love JavaScript but we can do better

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What’s Wrong with JS?

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What’s Wrong with JS?

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What’s Wrong with JS? 1100 pages

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What’s Wrong with JS? 1100 pages 176 pages

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What’s Wrong with JS?

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What’s Wrong with JS? • function

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What’s Wrong with JS? • function • return

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What’s Wrong with JS? • function • return • var

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What’s Wrong with JS? • function • return • var • ==

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What’s Wrong with JS? • function • return • var • == • for

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What’s Wrong with JS? • function • return • var • == • for • prototype-based OO

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What’s Right with JS?

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What’s Right with JS? • closures / blocks • namespaces • loosely typed variables • evented instead of threaded

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Starting Over Today

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Starting Over Today • Just give me the good parts

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Starting Over Today • Just give me the good parts • …and improve the expressiveness of business logic

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Starting Over Today • Just give me the good parts • …and improve the expressiveness of business logic • …but let me interoperate with all the existing great JS libraries

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Whirlwind Tour

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Whirlwind Tour intersection = -> { |ary1,ary2| ary1 & ary2 } Ruby

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Whirlwind Tour var intersection = function(ary1, ary2) { if (ary1.length > ary2.length) { var tmp = ary1; ary1 = ary2; ary2 = tmp; } var out = []; for (var i=0; i= 0) out.push(val); } return out; }

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Whirlwind Tour var intersection = function(ary1, ary2) { if (ary1.length > ary2.length) { var tmp = ary1; ary1 = ary2; ary2 = tmp; } var out = []; for (var i=0; i= 0) out.push(val); } return out; }

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Whirlwind Tour var intersection = function(ary1, ary2) { if (ary1.length > ary2.length) { var tmp = ary1; ary1 = ary2; ary2 = tmp; } var out = []; for (var i=0; i= 0) out.push(val); } return out; }

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var intersection = function(ary1, ary2) { if (ary1.length > ary2.length) { var tmp = ary1; ary1 = ary2; ary2 = tmp; } var out = []; for (var i=0; i= 0) out.push(val); } return out; } Whirlwind Tour

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var intersection = function(ary1, ary2) { if (ary1.length > ary2.length) { var tmp = ary1; ary1 = ary2; ary2 = tmp; } var out = []; for (var i=0; i= 0) out.push(val); } return out; } Whirlwind Tour

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var intersection = function(ary1, ary2) { if (ary1.length > ary2.length) { var tmp = ary1; ary1 = ary2; ary2 = tmp; } var out = []; for (var i=0; i= 0) out.push(val); } return out; } Whirlwind Tour X X X X X

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Whirlwind Tour intersection = (ary1, ary2) if (ary1.length > ary2.length) tmp = ary1; ary1 = ary2; ary2 = tmp out = [] for (i=0; i= 0) out.push(val) out

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Whirlwind Tour intersection = (ary1, ary2) if (ary1.length > ary2.length) tmp = ary1; ary1 = ary2; ary2 = tmp out = [] for (i=0; i= 0) out.push(val) out ->

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Whirlwind Tour intersection = (ary1, ary2) -> if (ary1.length > ary2.length) tmp = ary1; ary1 = ary2; ary2 = tmp out = [] for (i=0; i= 0) out.push(val) out

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Whirlwind Tour intersection = (ary1, ary2) -> if (ary1.length > ary2.length) tmp = ary1; ary1 = ary2; ary2 = tmp out = [] for (i=0; i= 0) out.push(val) out

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Whirlwind Tour intersection = (ary1, ary2) -> if (ary1.length > ary2.length) tmp = ary1; ary1 = ary2; ary2 = tmp out = [] for (i=0; i= 0) out.push(val) out

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Whirlwind Tour intersection = (ary1, ary2) -> if ary1.length > ary2.length tmp = ary1; ary1 = ary2; ary2 = tmp out = [] for (i=0; i= 0) out.push(val) out

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Whirlwind Tour intersection = (ary1, ary2) -> if ary1.length > ary2.length [ary2,ary1] = [ary1,ary2] out = [] for (i=0; i= 0) out.push(val) out

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Whirlwind Tour intersection = (ary1, ary2) -> out = [] for (i=0; i= 0) out.push(val) out if ary1.length > ary2.length [ary2,ary1] = [ary1,ary2]

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Whirlwind Tour intersection = (ary1, ary2) -> out = [] for (i=0; i= 0) out.push(val) out if ary1.length > ary2.lengt [ary2,ary1] = [ary1,ary2]

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Whirlwind Tour intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l out = [] for (i=0; i= 0) out.push(val) out

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Whirlwind Tour intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l out = [] for (i=0; i= 0) out.push(val) out

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Whirlwind Tour intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l out = (x for x in ary1 when ary2.indexOf(x) >= 0) out

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intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l out = (x for x in ary1 when ary2.indexOf(x) >= 0) out Whirlwind Tour ary1.

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intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l out = (x for x in ary1 when ary2.indexOf(x) >= 0) out Whirlwind Tour select { |x| ary2.indexOf(x) >= 0 }. ary1.

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intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l out = (x for x in ary1 when ary2.indexOf(x) >= 0) out Whirlwind Tour select { |x| ary2.indexOf(x) >= 0 }. ary1. map { |x| x }

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Whirlwind Tour intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l out = (x for x in ary1 when ary2.indexOf(x) >= 0) out

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Whirlwind Tour intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l out = (x for x in ary1 when ary2.indexOf(x) >= 0) out when x in ary2)

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intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l Whirlwind Tour out = out (x for x in ary1 when x in ary2)

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intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l Whirlwind Tour (x for x in ary1 when x in ary2)

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intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l (x for x in ary1 when x in ary2) Whirlwind Tour

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intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l (x for x in ary1 when x in ary2) Whirlwind Tour

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intersection = (ary1, ary2) -> [ary2,ary1] = [ary1,ary2] if ary1.length > ary2.l (x for x in ary1 when x in ary2) Whirlwind Tour

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Whirlwind var intersection; var __indexOf = Array.prototype.indexOf || function(item) { for (var i = 0, l = this.length; i < l; i++) { if (this[i] === item) return i; } return -1; }; intersection = function(ary1, ary2) { var x, _i, _len, _ref, _results; if (ary1.length > ary2.l) { _ref = [ary1, ary2], ary2 = _ref[0], ary1 = _ref[1]; } _results = []; for (_i = 0, _len = ary1.length; _i < _len; _i++) { x = ary1[_i]; if (__indexOf.call(ary2, x) >= 0) { _results.push(x); } } return _results; }; JavaScript

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Functions

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Functions say_hello = -> "Hello, world" # same as say_hello = -> "Hello, world" # invoked with say_hello()

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Functions say_hello = -> "Hello, world" # same as say_hello = -> "Hello, world" # invoked with say_hello() // compiles to: var say_hello; say_hello = function() { return "Hello, world"; }; say_hello();

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Functions say_hello = (name) -> "Hello, #{name}" say_hello("David") say_hello "David"

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Functions say_hello = (name) -> "Hello, #{name}" say_hello("David") say_hello "David" // compiles to: var say_hello; say_hello = function(name) { return "Hello, " + name; }; say_hello("David"); say_hello("David");

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Functions Using jQuery show_person = (person) -> $('#firstname').text(person.first_name) $('#lastname').text(person.last_name) $('button').click -> $('#status').text('Clicked')

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Classes

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Classes class Person constructor: (first_name, last_name) -> this.first_name = first_name this.last_name = last_name full_name: -> "#{this.first_name} #{this.last_name}"

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Classes class Person constructor: (first_name, last_name) -> @first_name = first_name @last_name = last_name full_name: -> "#{@first_name} #{@last_name}"

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Classes class Person constructor: (first_name, last_name) -> @first_name = first_name @last_name = last_name full_name: -> "#{@first_name} #{@last_name}"

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Classes class Person constructor: (@first_name, @last_name) -> full_name: -> "#{@first_name} #{@last_name}"

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Classes class Person constructor: (@first_name, @last_name) -> full_name: -> "#{@first_name} #{@last_name}" // compiles to: var Person; Person = (function() { function Person(first_name, last_name) { this.first_name = first_name; this.last_name = last_name; } Person.prototype.full_name = function() { return "" + this.first_name + " " + this.last_name; }; return Person; })();

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class Person constructor: (@first_name, @last_name) -> full_name: -> "#{@first_name} #{@last_name}" Classes: Inheritance

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class Person constructor: (@first_name, @last_name) -> full_name: -> "#{@first_name} #{@last_name}" class Employee extends Person constructor: (first, last, @title) -> super(first, last) full_name: -> "#{super}, #{@title}" // "class Employee extends Person" compiles to: var Employee; 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; }; Employee = (function() { __extends(Employee, Person); function Employee() { Employee.__super__.constructor.apply(this, arguments); } return Employee; })(); Classes: Inheritance

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class Person constructor: (@first_name, @last_name) -> full_name: -> "#{@first_name} #{@last_name}" class Employee extends Person constructor: (first, last, @title) -> super(first, last) full_name: -> "#{super}, #{@title}" employee = new Employee("Tim", "Cook", "CEO") console.log employee.full_name() # prints "Tim Cook, CEO" Classes: Inheritance

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Classes: Fat Arrow class PersonController constructor: (@person) -> display_person: -> $('#person_name').text(@person.full_name)

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Classes: Fat Arrow class PersonController constructor: (@person) -> display_person: -> $('#person_name').text(@person.full_name) person = # loaded from server

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Classes: Fat Arrow class PersonController constructor: (@person) -> display_person: -> $('#person_name').text(@person.full_name) person = # loaded from server controller = new PersonController(person)

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Classes: Fat Arrow class PersonController constructor: (@person) -> display_person: -> $('#person_name').text(@person.full_name) => person = # loaded from server controller = new PersonController(person) $('button').click controller.display_person # FAIL!

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Comparisons

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1 == '1' // true 1 == '1.0' // true 1 == true // true Comparisons JavaScript

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1 == '1' // true 1 == '1.0' // true 1 == true // true Comparisons JavaScript 1 === '1.0' // false 1 === '1' // false

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1 == '1' // true 1 == '1.0' // true 1 == true // true Comparisons JavaScript 1 === '1.0' // false 1 === '1' // false 1 is '1' # false 1 is '1.0' # false 1 is true # false 1 is 1 # true 1 is 1.0 # true CoffeeScript

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is odd = num % 2 is 1 isnt apple_rejection = app_lang isnt "Objective-C" in toddler = age in [1,2,3] not even = not odd and never_true = even and odd or fun = ruby or coffee_script Comparisons

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Existential Operator typeof person !== "undefined" && person !== null JavaScript

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Existential Operator typeof person !== "undefined" && person !== null JavaScript person? CoffeeScript

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Existential Operator $('#name').text(person.full_name) if person? person ?= new Person("David", "Kinney") beneficiary = spouse ? daughter zip = lottery.drawWinner?().address?.zipcode

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More Features

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Playing with Prototypes String::dasherize = -> this.replace /_/g, "-"

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Switch switch day when "Mon" then go work when "Tue" then go relax when "Thu" then go iceFishing when "Fri", "Sat" if day is bingoDay go bingo go dancing when "Sun" then go church else go work

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try-catch-ﬁnally try allHellBreaksLoose() catsAndDogsLivingTogether() catch error print error finally cleanUp()

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Stuff with Objects yearsOld = alice: 10, bob: 9, charlie: 11 ages = for child, age of yearsOld "#{child} is #{age}"

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Destructuring Objects futurists = sculptor: "Umberto Boccioni" painter: "Vladimir Burliuk" poet: name: "F.T. Marinetti" address: [ "Via Roma 42R" "Bellagio, Italy 22021" ] # extract name, street, and city {poet: {name, address: [street, city]}} = futurists

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Rails 3.1

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Rails 3.1

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Rails 3.1

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Rails 3.1

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Rails 3.1 $ -> more_link = $('') more_link.addClass 'more-link' more_link.text 'more' more_link.click -> $('#full-text').slideDown() $('#full-text').before(more_link).hide() app/assets/javascript/more_expander.js.coffee

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Rails 3.1 class Person constructor: (@first_name, @last_name) -> full_name: -> "#{@first_name} #{@last_name}" app/assets/javascript/person.js.coffee

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Rails 3.1 class Person constructor: (@first_name, @last_name) -> full_name: -> "#{@first_name} #{@last_name}" app/assets/javascript/person.js.coffee class Employee extends Person constructor: (first, last, @title) -> super(first, last) full_name: -> "#{super}, #{@title}" app/assets/javascript/employee.js.coffee

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Next Steps Website coffeescript.org PeepCode Screencast peepcode.com/ products/coffeescript PragProg Book pragprog.com/book/ tbcoffee/coffeescript

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Rich UIs Agile development Rails and mobile for enterprise