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

FOWA 2011

2. Sam Stephenson 37signals
3. Better JavaScript with CoffeeScript
4. CoffeeScript is Beautiful & I Never Want to Write Plain JavaScript Again
5. A Brief Personal History
7. names = people.map do |person| person.name.capitalize end
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); }
9. . prototype .
10. var names = people.map( function(person) { return person.name. capitalize(); } );
11. var names = people.map( function(person) { return person.name. capitalize(); } );
12. var names = people.map( function(person) { return person.name. capitalize(); } );
14. We’re Stuck With JavaScript
15. Compile to JavaScript
16. Google Web Toolkit
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); } }
18. <?xml version="1.0" encoding="UTF-8"?> <module rename-to='com_example_gwt_helloworld'> <!-- Inherit the core Web Toolkit stuff. --> <inherits name='com.google.gwt.user.User'/> <inherits name='com.google.gwt.user.theme.standard.Standard'/> <!-- Specify the app entry point class. --> <entry-point class='com.example.gwt.helloworld.client.HelloWorld'/> </module> <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd"> <web-app> <!-- Default page to serve --> <welcome-file-list> <welcome-file>Com_example_gwt_helloworld.html</welcome-file> </welcome-file-list> </web-app>
20. function hello(){var l='',F='" for "gwt:onLoadErrorFn"',D='" for "gwt:onPropert yErrorFn"',n='"><\/script>',p='#',r='/',vb='02EDD05CEF7D978C649BF91CC66AB635.ca che.html',sb='28600060343BDDEB1FD83487846D090C.cache.html',ub='9EDF9C067C3A475F 6EA7A16003CA4979.cache.html',Fb='<script defer="defer">hello.onInjectionDone(\' hello\')<\/script>',dc='<script id="',A='=',q='?',C='Bad handler "',tb='D69BADE 681FFFC6071DFA4FC25EF1DC5.cache.html',Eb='DOMContentLoaded',wb='F26BFE33DA14C23 176C7BC08D58AA43F.cache.html',o='SCRIPT',cc='__gwt_marker_hello',s='base',nb='b egin',cb='bootstrap',u='clear.cache.gif',z='content',bc='end',lb='gecko',mb='ge cko1_8',yb='gwt.hybrid',xb='gwt/standard/standard.css',E='gwt:onLoadErrorFn',B= 'gwt:onPropertyErrorFn',y='gwt:property',Db='head',qb='hosted.html?hello',Cb='h ref',kb='ie6',ab='iframe',t='img',bb="javascript:''",zb='link',pb='loadExternal Refs',v='meta',eb='moduleRequested',ac='moduleStartup',jb='msie',w='name',gb='o pera',db='position:absolute;width:0;height:0;border:none',Ab='rel',ib='safari', rb='selectingPermutation',x='startup',m='hello',Bb='stylesheet',ob='unknown',fb ='user.agent',hb='webkit';var fc=window,k=document,ec=fc.__gwtStatsEvent?functi on(a){return fc.__gwtStatsEvent(a)}:null,zc,pc,kc,jc=l,sc={},Cc=[],yc=[],ic=[], vc,xc;ec&&ec({moduleName:m,subSystem:x,evtGroup:cb,millis:(new Date()).getTime( ),type:nb});if(!fc.__gwt_stylesLoaded){fc.__gwt_stylesLoaded={}}if(!fc.__gwt_sc riptsLoaded){fc.__gwt_scriptsLoaded={}}function oc(){var b=false;try{b=fc.exter nal&&(fc.external.gwtOnLoad&&fc.location.search.indexOf(yb)==-1)}catch(a){}oc=f unction(){return b};return b}function rc(){if(zc&&pc){var c=k.getElementById(m) ;var b=c.contentWindow;if(oc()){b.__gwt_getProperty=function(a){return lc(a)}}h ello=null;b.gwtOnLoad(vc,m,jc);ec&&ec({moduleName:m,subSystem:x,evtGroup:ac,mil lis:(new Date()).getTime(),type:bc})}};function mc(){var j,h=cc,i;k.write(dc+h+ n);i=k.getElementById(h);j=i&&i.previousSibling;while(j&&j.tagName!=o){j=j.prev iousSibling}function f(b){var a=b.lastIndexOf(p);if(a==-1){a=b.length}var c=b.i ndexOf(q);if(c==-1){c=b.length}var d=b.lastIndexOf(r,Math.min(c,a));return d>=0 ?b.substring(0,d+1):l};if(j&&j.src){jc=f(j.src)}if(jc==l){var e=k.getElementsBy TagName(s);if(e.length>0){jc=e[e.length-1].href}else{jc=f(k.location.href)}}els e if(jc.match(/^\w+:\/\//)){}else{var g=k.createElement(t);g.src=jc+u;jc=f(g.sr
21. Pyjamas
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("<b>Hello World</b> (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()
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
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
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
26. Objective-J
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
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.
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.
31. It’s Just JavaScript $(function() { $("body").html("Hello world"); });
32. It’s Just JavaScript $ -> $("body").html "Hello world"
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.
36. Good Part: Private by default
37. Good Part: Private by default (function() { /* your program here */ }).call(this);
38. Good Part: No more var
39. Good Part: No more var lastClick = 0 $("a").click -> now = new Date().getTime() if now - lastClick > 100 $("#message").show() lastClick = now
40. Good Part: No more var var lastClick = 0 $("a").click -> var now = new Date().getTime() if now - lastClick > 100 $("#message").show() lastClick = now
41. Good Part: Strict comparisons
42. Good Part: Strict comparisons == vs. ===
43. Good Part: Strict comparisons "true" == true // true "true" === true // false "0" == false // true "0" == 0 // true 0 === false // false "" == false // true
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
45. Good Part: Runs anywhere
46. Good Part: Runs anywhere JSLint compliant
47. 10 Things I Love About CoffeeScript
48. 1. Function Syntax
49. 1. Function Syntax function greet (name) { return "Hello " + name; }
50. 1. Function Syntax greet = (name) -> "Hello " + name
51. 1. Function Syntax $("a").click(function(event) { $(this).addClass("busy"); });
52. 1. Function Syntax $("a").click (event) -> $(this).addClass "busy"
53. 2. Significant Whitespace
54. 2. Significant Whitespace if (url) { $.get(url, function(data) { return $("#result").html(data); }); } else { $("#error").show(); }
55. 2. Significant Whitespace if url $.get url, (data) -> $("#result").html data else $("#error").show()
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); } }); };
57. 2. Significant Whitespace readConfiguration = (callback) -> path.exists filename, (err, exists) -> if exists fs.readFile filename, callback else callback false
58. 3. Bare Objects
59. 3. Bare Objects $(this).css({ top: "20px", left: "-20px" });
60. 3. Bare Objects $(this).css top: "20px", left: "-20px"
61. 3. Bare Objects $.ajax({ url: path, timeout: 5, data: { from: "workspace" }, dataType: "html", success: function(data) { return $("#result").html(data); } });
62. 3. Bare Objects $.ajax url: path, timeout: 5, data: from: "workspace", dataType: "html", success: (data) -> $("#result").html data
63. 3. Bare Objects person = name: "Sam" age: 27 profession: "Programmer"
64. 4. Everything’s an Expression
65. 4. Everything’s an Expression switch keyCode when 38 command = "previous" when 40 command = "next" when 13 command = "select"
66. 4. Everything’s an Expression command = switch keyCode when 38 then "previous" when 40 then "next" when 13 then "select"
67. 4. Everything’s an Expression getCommand = (keyCode) -> switch keyCode when 38 then "previous" when 40 then "next" when 13 then "select"
68. 5. Comprehensions
69. 5. Comprehensions names = [] for person in people names.push capitalize person.name
70. 5. Comprehensions names = for person in people capitalize person.name
71. 5. Comprehensions ages = (person.age for person in people)
72. 5. Comprehensions names = for person in people when age > 27 capitalize person.name
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; })();
74. 6. Classes & Inheritance
75. 6. Classes & Inheritance class Photo constructor: (url) -> this.url = url createElement: -> $("<img>").attr "src", this.url
76. 6. Classes & Inheritance class Photo constructor: (url) -> this.url = url createElement: -> $("<img>").attr "src", this.url
77. 6. Classes & Inheritance class Photo constructor: (url) -> @url = url createElement: -> $("<img>").attr "src", @url
78. 6. Classes & Inheritance class Photo constructor: (@url) -> createElement: -> $("<img>").attr "src", @url
79. 6. Classes & Inheritance class Thumbnail extends Photo createElement: -> $el = super $el.height 100
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; })();
81. 7. Bound Functions
82. 7. Bound Functions class PersonView constructor: (@person, @el) -> request: -> $.get @person.url, (data) -> $(@el).html data
83. 7. Bound Functions class PersonView constructor: (@person, @el) -> request: -> $.get @person.url, (data) -> $(@el).html data
84. 7. Bound Functions function request () { $.get(this.person.url, (function(data) { $(this.el).html(data); }).bind(this) ) }
85. 7. Bound Functions class PersonView constructor: (@person, @el) -> request: -> $.get @person.url, (data) => $(@el).html data
86. 7. Bound Functions class PersonView constructor: (@person, @el) -> $(@el).bind "click", @showName showName: => $(@el).html @person.name
87. 8. Conditionals
88. 8. Conditionals @request() if @isActive() return unless $("li").length
89. 8. Conditionals result + 10 if result?
90. 8. Conditionals @panel?.restore()
91. 8. Conditionals @panel.url ?= window.location
92. 9. Destructuring Assignment
93. 9. Destructuring Assignment name = person.name
94. 9. Destructuring Assignment name = person.name {name} = person
95. 9. Destructuring Assignment name = person.name {name} = person {name, age} = person
96. 9. Destructuring Assignment [first, last] = person.name.split " "
97. 10. String Syntax
98. 10. String Syntax greet = (name) -> "Hello #{name}"
99. 10. String Syntax greet = (name) -> "Hello #{name.toUpperCase()}"
100. 10. String Syntax render = (person) -> """ <div class="person"> <a href="#{person.url}">#{person.name}</a> <span>#{person.profession}</span> </div> """
101. How To Use It
104. Command Line $ npm install -g coffee-script
105. Command Line $ coffee -c hello.coffee $ cat hello.js (function() { alert("hello"); }).call(this);
106. Command Line $ coffee -cw hello.coffee
107. Rails 3.1 Sprockets https://github.com/sstephenson/sprockets
108. Node.js Stitch https://github.com/sstephenson/stitch
109. Thank You @sstephenson
110. http://coffeescript.org/