CoffeeScript is Beautiful & I Never Want to Write Plain JavaScript Again

FOWA 2011

Transcript

1. View Slide

2. Sam Stephenson
   37signals
   

   View Slide

3. Better JavaScript
   with CoffeeScript
   

   View Slide

4. CoffeeScript is
   Beautiful & I Never
   Want to Write Plain
   JavaScript Again
   

   View Slide

5. A Brief Personal History
   

   View Slide

6. View Slide

7. names =
   people.map do |person|
   person.name.capitalize
   end
   

   View Slide

8. var names = [];
   for (var i = 0, l = people.length;
   i < l; i++) {
   var person = people[i];
   var name = person.name.
   slice(0, 1).toUpperCase() +
   person.name.slice(1);
   names.push(name);
   }
   

   View Slide

9. .
   prototype
   .
   

   View Slide

10. var names = people.map(
    function(person) {
    return person.name.
    capitalize();
    }
    );
    

    View Slide

11. var names = people.map(
    function(person) {
    return person.name.
    capitalize();
    }
    );
    

    View Slide

12. var names = people.map(
    function(person) {
    return person.name.
    capitalize();
    }
    );
    

    View Slide

13. View Slide

14. We’re Stuck With JavaScript
    

    View Slide

15. Compile to JavaScript
    

    View Slide

16. Google Web Toolkit
    

    View Slide

17. package com.example.gwt.helloworld.client;
    import com.google.gwt.core.client.EntryPoint;
    import com.google.gwt.event.dom.client.ClickEvent;
    import com.google.gwt.event.dom.client.ClickHandler;
    import com.google.gwt.user.client.Window;
    import com.google.gwt.user.client.ui.Button;
    import com.google.gwt.user.client.ui.Label;
    import com.google.gwt.user.client.ui.RootPanel;
    public class HelloWorld implements EntryPoint {
    @Override
    public void onModuleLoad() {
    Label label = new Label("Hello world");
    Button button = new Button("Say something");
    button.addClickHandler(new ClickHandler() {
    @Override
    public void onClick(ClickEvent event) {
    Window.alert("Hello again");
    }
    });
    RootPanel.get().add(label);
    RootPanel.get().add(button);
    }
    }
    

    View Slide

18. 
    
    
    
    
    
    
    
    
    br/>PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
    "http://java.sun.com/dtd/web-app_2_3.dtd">
    
    
    
    Com_example_gwt_helloworld.html
    
    
    

    View Slide

19. View Slide

20. function hello(){var l='',F='" for "gwt:onLoadErrorFn"',D='" for "gwt:onPropert
    yErrorFn"',n='">',p='#',r='/',vb='02EDD05CEF7D978C649BF91CC66AB635.ca
    che.html',sb='28600060343BDDEB1FD83487846D090C.cache.html',ub='9EDF9C067C3A475F
    6EA7A16003CA4979.cache.html',Fb='hello.onInjectionDone(\'<br/>hello\')<\/script>',dc='<script id="',A='=',q='?',C='Bad handler "',tb='D69BADE<br/>681FFFC6071DFA4FC25EF1DC5.cache.html',Eb='DOMContentLoaded',wb='F26BFE33DA14C23<br/>176C7BC08D58AA43F.cache.html',o='SCRIPT',cc='__gwt_marker_hello',s='base',nb='b<br/>egin',cb='bootstrap',u='clear.cache.gif',z='content',bc='end',lb='gecko',mb='ge<br/>cko1_8',yb='gwt.hybrid',xb='gwt/standard/standard.css',E='gwt:onLoadErrorFn',B=<br/>'gwt:onPropertyErrorFn',y='gwt:property',Db='head',qb='hosted.html?hello',Cb='h<br/>ref',kb='ie6',ab='iframe',t='img',bb="javascript:''",zb='link',pb='loadExternal<br/>Refs',v='meta',eb='moduleRequested',ac='moduleStartup',jb='msie',w='name',gb='o<br/>pera',db='position:absolute;width:0;height:0;border:none',Ab='rel',ib='safari',<br/>rb='selectingPermutation',x='startup',m='hello',Bb='stylesheet',ob='unknown',fb<br/>='user.agent',hb='webkit';var fc=window,k=document,ec=fc.__gwtStatsEvent?functi<br/>on(a){return fc.__gwtStatsEvent(a)}:null,zc,pc,kc,jc=l,sc={},Cc=[],yc=[],ic=[],<br/>vc,xc;ec&&ec({moduleName:m,subSystem:x,evtGroup:cb,millis:(new Date()).getTime(<br/>),type:nb});if(!fc.__gwt_stylesLoaded){fc.__gwt_stylesLoaded={}}if(!fc.__gwt_sc<br/>riptsLoaded){fc.__gwt_scriptsLoaded={}}function oc(){var b=false;try{b=fc.exter<br/>nal&&(fc.external.gwtOnLoad&&fc.location.search.indexOf(yb)==-1)}catch(a){}oc=f<br/>unction(){return b};return b}function rc(){if(zc&&pc){var c=k.getElementById(m)<br/>;var b=c.contentWindow;if(oc()){b.__gwt_getProperty=function(a){return lc(a)}}h<br/>ello=null;b.gwtOnLoad(vc,m,jc);ec&&ec({moduleName:m,subSystem:x,evtGroup:ac,mil<br/>lis:(new Date()).getTime(),type:bc})}};function mc(){var j,h=cc,i;k.write(dc+h+<br/>n);i=k.getElementById(h);j=i&&i.previousSibling;while(j&&j.tagName!=o){j=j.prev<br/>iousSibling}function f(b){var a=b.lastIndexOf(p);if(a==-1){a=b.length}var c=b.i<br/>ndexOf(q);if(c==-1){c=b.length}var d=b.lastIndexOf(r,Math.min(c,a));return d>=0<br/>?b.substring(0,d+1):l};if(j&&j.src){jc=f(j.src)}if(jc==l){var e=k.getElementsBy<br/>TagName(s);if(e.length>0){jc=e[e.length-1].href}else{jc=f(k.location.href)}}els<br/>e if(jc.match(/^\w+:\/\//)){}else{var g=k.createElement(t);g.src=jc+u;jc=f(g.sr<br/>

    View Slide

21. Pyjamas
    

    View Slide

22. import pyjd # this is dummy in pyjs.
    from pyjamas.ui.RootPanel import RootPanel
    from pyjamas.ui.Button import Button
    from pyjamas.ui.HTML import HTML
    from pyjamas.ui.Label import Label
    from pyjamas import Window
    import pygwt
    def greet(fred):
    fred.setText("No, really click me!")
    Window.alert("Hello, AJAX!")
    if __name__ == '__main__':
    pyjd.setup("public/Hello.html?fred=foo#me")
    b = Button("Click me", greet, StyleName='teststyle')
    h = HTML("Hello World (html)", StyleName='teststyle')
    l = Label("Hello World (label)", StyleName='teststyle')
    base = HTML("Hello from %s" % pygwt.getModuleBaseURL(),
    StyleName='teststyle')
    RootPanel().add(b)
    RootPanel().add(h)
    RootPanel().add(l)
    RootPanel().add(base)
    pyjd.run()
    

    View Slide

23. I love/prefer {insert AJAX / Javascript framework here},
    how do I use it?
    Not being funny or anything, but unless you have the
    resources of google or lots of money or lots of time, or you
    can gather enough people to make it so that everyone has
    less work to do: you don't.
    huh? why?? Some of the widgets in DojoX / Ext-JS are
    really cute! I want them! waaah!
    You are not in Kansas any more. Pyjamas is declarative-
    style programming, using a "real" programming language.
    All those widget-sets were designed to be driven from
    inside HTML (a style of web development which, using
    Pyjamas, you have just left far behind) and by inserting
    javascript snippets into the HTML. If you try that with a
    Pyjamas app, you are not only likely to get yourself into an
    

    View Slide

24. I love/prefer {insert AJAX / Javascript framework here},
    how do I use it?
    Not being funny or anything, but unless you have the
    resources of google or lots of money or lots of time, or you
    can gather enough people to make it so that everyone has
    less work to do: you don't.
    huh? why?? Some of the widgets in DojoX / Ext-JS are
    really cute! I want them! waaah!
    You are not in Kansas any more. Pyjamas is declarative-
    style programming, using a "real" programming language.
    All those widget-sets were designed to be driven from
    inside HTML (a style of web development which, using
    Pyjamas, you have just left far behind) and by inserting
    javascript snippets into the HTML. If you try that with a
    Pyjamas app, you are not only likely to get yourself into an
    

    View Slide

25. I love/prefer {insert AJAX / Javascript framework here},
    how do I use it?
    Not being funny or anything, but unless you have the
    resources of google or lots of money or lots of time, or you
    can gather enough people to make it so that everyone has
    less work to do: you don't.
    huh? why?? Some of the widgets in DojoX / Ext-JS are
    really cute! I want them! waaah!
    You are not in Kansas any more. Pyjamas is declarative-
    style programming, using a "real" programming language.
    All those widget-sets were designed to be driven from
    inside HTML (a style of web development which, using
    Pyjamas, you have just left far behind) and by inserting
    javascript snippets into the HTML. If you try that with a
    Pyjamas app, you are not only likely to get yourself into an
    

    View Slide

26. Objective-J
    

    View Slide

27. @implementation AppController : CPObject { }
    - (void)applicationDidFinishLaunching:(CPNotification)note
    {
    theWindow = [[CPWindow alloc] initWithContentRect:CGRectMakeZero()
    styleMask:CPBorderlessBridgeWindowMask];
    contentView = [theWindow contentView];
    var label = [[CPTextField alloc] initWithFrame:CGRectMakeZero()];
    [label setStringValue:@"Hello World!"];
    [label setFont:[CPFont boldSystemFontOfSize:24.0]];
    [label sizeToFit];
    [label setAutoresizingMask:CPViewMinXMargin | CPViewMaxXMargin];
    [label setFrameOrigin:CGRectMake(100,100)];
    [contentView addSubview:label];
    [theWindow orderFront:self];
    }
    @end
    

    View Slide

28. View Slide

29. CoffeeScript is a little language that
    compiles into JavaScript.
    Underneath all of those embarrassing
    braces and semicolons, JavaScript has
    always had a gorgeous object model
    at its heart. CoffeeScript is an attempt
    to expose the good parts of JavaScript
    in a simple way.
    The golden rule of CoffeeScript is: “It’s
    just JavaScript”. The code compiles
    one-to-one into the equivalent JS, and
    there is no interpretation at runtime.
    

    View Slide

30. CoffeeScript is a little language that
    compiles into JavaScript.
    Underneath all of those embarrassing
    braces and semicolons, JavaScript has
    always had a gorgeous object model
    at its heart. CoffeeScript is an attempt
    to expose the good parts of JavaScript
    in a simple way.
    The golden rule of CoffeeScript is: “It’s
    just JavaScript”. The code compiles
    one-to-one into the equivalent JS, and
    there is no interpretation at runtime.
    

    View Slide

31. It’s Just JavaScript
    $(function() {
    $("body").html("Hello world");
    });
    

    View Slide

32. It’s Just JavaScript
    $ ->
    $("body").html "Hello world"
    

    View Slide

33. CoffeeScript is a little language that
    compiles into JavaScript.
    Underneath all of those embarrassing
    braces and semicolons, JavaScript has
    always had a gorgeous object model
    at its heart. CoffeeScript is an attempt
    to expose the good parts of JavaScript
    in a simple way.
    The golden rule of CoffeeScript is: “It’s
    just JavaScript”. The code compiles
    one-to-one into the equivalent JS, and
    there is no interpretation at runtime.
    

    View Slide

34. View Slide

35. View Slide

36. Good Part:
    Private by default
    

    View Slide

37. Good Part:
    Private by default
    (function() {
    /* your program here */
    }).call(this);
    

    View Slide

38. Good Part:
    No more var
    

    View Slide

39. Good Part:
    No more var
    lastClick = 0
    $("a").click ->
    now = new Date().getTime()
    if now - lastClick > 100
    $("#message").show()
    lastClick = now
    

    View Slide

40. Good Part:
    No more var
    var lastClick = 0
    $("a").click ->
    var now = new Date().getTime()
    if now - lastClick > 100
    $("#message").show()
    lastClick = now
    

    View Slide

41. Good Part:
    Strict comparisons
    

    View Slide

42. Good Part:
    Strict comparisons
    == vs. ===
    

    View Slide

43. Good Part:
    Strict comparisons
    "true" == true // true
    "true" === true // false
    "0" == false // true
    "0" == 0 // true
    0 === false // false
    "" == false // true
    

    View Slide

44. Good Part:
    Strict comparisons
    "true" is true // false
    "true" is "true" // true
    "0" is false // false
    "0" is 0 // false
    0 is 0 // true
    "" is false // false
    

    View Slide

45. Good Part:
    Runs anywhere
    

    View Slide

46. Good Part:
    Runs anywhere
    JSLint compliant
    

    View Slide

47. 10 Things I Love
    About CoffeeScript
    

    View Slide

48. 1. Function Syntax
    

    View Slide

49. 1. Function Syntax
    function greet (name) {
    return "Hello " + name;
    }
    

    View Slide

50. 1. Function Syntax
    greet = (name) ->
    "Hello " + name
    

    View Slide

51. 1. Function Syntax
    $("a").click(function(event) {
    $(this).addClass("busy");
    });
    

    View Slide

52. 1. Function Syntax
    $("a").click (event) ->
    $(this).addClass "busy"
    

    View Slide

53. 2. Significant Whitespace
    

    View Slide

54. 2. Significant Whitespace
    if (url) {
    $.get(url, function(data) {
    return $("#result").html(data);
    });
    } else {
    $("#error").show();
    }
    

    View Slide

55. 2. Significant Whitespace
    if url
    $.get url, (data) ->
    $("#result").html data
    else
    $("#error").show()
    

    View Slide

56. 2. Significant Whitespace
    var readConfiguration = function(callback) {
    return path.exists(filename, function(err, exists) {
    if (exists) {
    return fs.readFile(filename, callback);
    } else {
    return callback(false);
    }
    });
    };
    

    View Slide

57. 2. Significant Whitespace
    readConfiguration = (callback) ->
    path.exists filename, (err, exists) ->
    if exists
    fs.readFile filename, callback
    else
    callback false
    

    View Slide

58. 3. Bare Objects
    

    View Slide

59. 3. Bare Objects
    $(this).css({ top: "20px", left: "-20px" });
    

    View Slide

60. 3. Bare Objects
    $(this).css top: "20px", left: "-20px"
    

    View Slide

61. 3. Bare Objects
    $.ajax({
    url: path,
    timeout: 5,
    data: {
    from: "workspace"
    },
    dataType: "html",
    success: function(data) {
    return $("#result").html(data);
    }
    });
    

    View Slide

62. 3. Bare Objects
    $.ajax
    url: path,
    timeout: 5,
    data:
    from: "workspace",
    dataType: "html",
    success: (data) ->
    $("#result").html data
    

    View Slide

63. 3. Bare Objects
    person =
    name: "Sam"
    age: 27
    profession: "Programmer"
    

    View Slide

64. 4. Everything’s an Expression
    

    View Slide

65. 4. Everything’s an Expression
    switch keyCode
    when 38
    command = "previous"
    when 40
    command = "next"
    when 13
    command = "select"
    

    View Slide

66. 4. Everything’s an Expression
    command = switch keyCode
    when 38 then "previous"
    when 40 then "next"
    when 13 then "select"
    

    View Slide

67. 4. Everything’s an Expression
    getCommand = (keyCode) ->
    switch keyCode
    when 38 then "previous"
    when 40 then "next"
    when 13 then "select"
    

    View Slide

68. 5. Comprehensions
    

    View Slide

69. 5. Comprehensions
    names = []
    for person in people
    names.push capitalize person.name
    

    View Slide

70. 5. Comprehensions
    names = for person in people
    capitalize person.name
    

    View Slide

71. 5. Comprehensions
    ages = (person.age for person in people)
    

    View Slide

72. 5. Comprehensions
    names = for person in people when age > 27
    capitalize person.name
    

    View Slide

73. 5. Comprehensions
    var names, person;
    names = (function() {
    var _i, _len, _results;
    _results = [];
    for (_i = 0, _len = people.length; _i < _len; _i++) {
    person = people[_i];
    if (age > 27) {
    _results.push(capitalize(person.name));
    }
    }
    return _results;
    })();
    

    View Slide

74. 6. Classes & Inheritance
    

    View Slide

75. 6. Classes & Inheritance
    class Photo
    constructor: (url) ->
    this.url = url
    createElement: ->
    $("").attr "src", this.url
    

    View Slide

76. 6. Classes & Inheritance
    class Photo
    constructor: (url) ->
    this.url = url
    createElement: ->
    $("").attr "src", this.url
    

    View Slide

77. 6. Classes & Inheritance
    class Photo
    constructor: (url) ->
    @url = url
    createElement: ->
    $("").attr "src", @url
    

    View Slide

78. 6. Classes & Inheritance
    class Photo
    constructor: (@url) ->
    createElement: ->
    $("").attr "src", @url
    

    View Slide

79. 6. Classes & Inheritance
    class Thumbnail extends Photo
    createElement: ->
    $el = super
    $el.height 100
    

    View Slide

80. 6. Classes & Inheritance
    var Thumbnail;
    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;
    };
    Thumbnail = (function() {
    __extends(Thumbnail, Photo);
    function Thumbnail() {
    Thumbnail.__super__.constructor.apply(this, arguments);
    }
    Thumbnail.prototype.createElement = function() {
    var $el;
    $el = Thumbnail.__super__.createElement.apply(this, arguments);
    return $el.height(100);
    };
    return Thumbnail;
    })();
    

    View Slide

81. 7. Bound Functions
    

    View Slide

82. 7. Bound Functions
    class PersonView
    constructor: (@person, @el) ->
    request: ->
    $.get @person.url, (data) ->
    $(@el).html data
    

    View Slide

83. 7. Bound Functions
    class PersonView
    constructor: (@person, @el) ->
    request: ->
    $.get @person.url, (data) ->
    $(@el).html data
    

    View Slide

84. 7. Bound Functions
    function request () {
    $.get(this.person.url,
    (function(data) {
    $(this.el).html(data);
    }).bind(this)
    )
    }
    

    View Slide

85. 7. Bound Functions
    class PersonView
    constructor: (@person, @el) ->
    request: ->
    $.get @person.url, (data) =>
    $(@el).html data
    

    View Slide

86. 7. Bound Functions
    class PersonView
    constructor: (@person, @el) ->
    $(@el).bind "click", @showName
    showName: =>
    $(@el).html @person.name
    

    View Slide

87. 8. Conditionals
    

    View Slide

88. 8. Conditionals
    @request() if @isActive()
    return unless $("li").length
    

    View Slide

89. 8. Conditionals
    result + 10 if result?
    

    View Slide

90. 8. Conditionals
    @panel?.restore()
    

    View Slide

91. 8. Conditionals
    @panel.url ?= window.location
    

    View Slide

92. 9. Destructuring Assignment
    

    View Slide

93. 9. Destructuring Assignment
    name = person.name
    

    View Slide

94. 9. Destructuring Assignment
    name = person.name
    {name} = person
    

    View Slide

95. 9. Destructuring Assignment
    name = person.name
    {name} = person
    {name, age} = person
    

    View Slide

96. 9. Destructuring Assignment
    [first, last] = person.name.split " "
    

    View Slide

97. 10. String Syntax
    

    View Slide

98. 10. String Syntax
    greet = (name) ->
    "Hello #{name}"
    

    View Slide

99. 10. String Syntax
    greet = (name) ->
    "Hello #{name.toUpperCase()}"
    

    View Slide

100. 10. String Syntax
     render = (person) ->
     """
     
     #{person.name}
     #{person.profession}
     
     """
     

     View Slide

101. How To
     Use It
     

     View Slide

102. View Slide

103. View Slide

104. Command Line
     $ npm install -g coffee-script
     

     View Slide

105. Command Line
     $ coffee -c hello.coffee
     $ cat hello.js
     (function() {
     alert("hello");
     }).call(this);
     

     View Slide

106. Command Line
     $ coffee -cw hello.coffee
     

     View Slide

107. Rails 3.1
     Sprockets
     https://github.com/sstephenson/sprockets
     

     View Slide

108. Node.js
     Stitch
     https://github.com/sstephenson/stitch
     

     View Slide

109. Thank
     You
     @sstephenson
     

     View Slide

110. http://coffeescript.org/
     

     View Slide