Apps with millions lines of code maintained by hundreds of SWEs. Can vanilla JS + HTML5 do the job? If not, what can? TypeScript? Dart?

1. Huge Web Apps
daniel.steigerwald.cz

2. ● independent software gardener
● web applications consultant and trainer
● Google Developer Expert
● libertarian svobodni.cz
About Me

3. What is a Huge App?

4. sooner or later
The Pain.

5. Symptoms
● fixing bugs creates new bugs
● rotten code
● developers paralyzed by fear
● technical debts
● reinventing the wheel
● perpetual rewriting
= stress driven development

6. Remedies
● optional static typing
● user interface frameworks
● clean code
● clean architecture
● good infrastructure
● unit tests
● senior developers :-)

7. Optional Static Typing
dynamic versus static

8. Keeping Your Code in Check!
Make it hard to do the wrong thing.

9. Makes code more readable.
function(duck) { // which duck?
duck.quack();
}

10. Makes code more robust.
function(duck) {
duck.quack(); // does quack?
}

11. No JavaScript?
The king is dead, long live the king!

12. Closure, Dart, TypeScript
Born to be wild tamed.

13. Google Closure
That's how Google build apps.

14. function fn(duck) {
duck.quack();
}

15. /**
* @param {Duck} duck
*/
function fn(duck) {
duck.quack();
}

16. Dart
That's how Google will build apps.

17. fn(duck) {
duck.quack();
}

18. fn(Duck duck) {
duck.quack();
}

19. TypeScript
Microsoft did the right thing.

20. function(duck) {
duck.quack();
}

21. function(duck: Duck) {
duck.quack();
}

22. github.com/borisyankov/DefinitelyTyped
fixing legacy code

23. Ace Cloud9 Editor AmCharts AngularJS Arbiter async Backbone.js Backbone Relational
Bootbox Bootstrap bootstrap-notify bootstrap.datepicker Box2DWeb Breeze Browser Harness
CasperJS Cheerio Chosen Chrome CodeMirror Commander d3.js docCookies domo dust
EaselJS ember.js EpicEditor expect.js Express Ext JS Fabric.js Fancybox File API: Directories
and System File API: Writer Finite State Machine Firebase Firefox FlexSlider Foundation
FPSMeter FullCalendar Gamepad glDatePicker GoJS GreenSock Animation Platform Grunt JS
Google API Client Google App Engine Channel API GoogleMaps Google Geolocation Google
Page Speed Online API Google Translate API Google Url Shortener Hammer.js Handlebars
Highcharts highlight.js History.js Humane.js i18next iCheck Impress.js Intl iScroll jake Jasmine
Jasmine-jQuery JointJS jQRangeSlider jQuery jQuery Mobile jQuery UI jQuery.Address jQuery.
areYouSure jQuery.autosize jQuery.BBQ jQuery.contextMenu jQuery.clientSideLogging jQuery.
Colorbox jQuery.Cookie jQuery.Cycle jQuery.dataTables jQuery.dynatree jQuery.Flot jQuery.
form jQuery.Globalize jQuery.gridster jQuery.jNotify jQuery.noty jQuery.pickadate jQuery.
payment jQuery.scrollTo jQuery.simplePagination jquery.superLink jQuery.timeago jQuery.
Timepicker jQuery.TinyCarousel jQuery.TinyScrollbar jQuery.Transit jQuery.Validation jQuery.
Watermark jScrollPane JSDeferred JSONEditorOnline jStorage JWPlayer KeyboardJS
Knockback Knockout.js Knockout.DeferredUpdates Knockout.ES5 Knockout.Mapping
Knockout.Postbox Knockout.Validation Knockout.Viewmodel ko.editables KoLite Leaflet
Libxmljs ladda Levelup linq.js Livestamp.js Logg Marked Meteor Modernizr Moment.js
MongoDB Mousetrap Mustache.js Node.js node_redis node-ffi node_zeromq node-sqlserver
Numeral.js Parallel.js PDF.js Persona PhantomJS PhoneGap PixiJS Platform PouchDB
PreloadJS QUnit Raven.js Rickshaw Restify Royalslider Rx.js Raphael Restangular require.js
Sammy.js Select2 Sencha Touch SharePoint SignalR Sinon SlickGrid socket.io SockJS
SoundJS Spin stripe Store.js Sugar Swiper SwipeView Tags Manager Teechart three.js Toastr
trunk8 TweenJS tween.js twitter-bootstrap-wizard Ubuntu Unity Web API Underscore.js
Underscore.js Underscore-ko.js UUID.js Viewporter Vimeo WebRTC WinJS WinRT YouTube
YouTube Analytics API YouTube Data API Zepto.js Zynga Scroller ZeroClipboard

24. User Interface
Beyond the jQuery Backbone.

25. Why Backbone is not enough?
It doesn’t aspire to be anything more than a
lightweight library for models and collections.

26. Why Backbone is not enough?
Default Backbone view is simply too simple.

27. todomvc.com

28. Handlebars, Mustache, Underscore templates, Dust,
Jade and many others...
HTML templates based only on
string concatenation are
obsolete.

29. Don't hold state in DOM.
Use DOM only as app state projection.

30. Partial DOM updates sucks.
this.$('#filters li a')
.removeClass('selected')
.filter('[href="#/' + (app.TodoFilter || '') + '"]')
.addClass('selected');

31. Say no to boilerplate code.
especially for view updates

32. Angular, Ember, React
view updates done well

33. /** @jsx React.DOM */
var HelloMessage = React.createClass({
render: function() {
return <div>{'Hello ' + this.props.name}</div>;
}
});
React.renderComponent(<HelloMessage name="John" />, el);
Facebook React

34. var Nav, Profile;
// Input (JSX):
var app =
<Nav color="blue">
<Profile>click</Profile>
</Nav>;
// Output (JS):
var app = Nav({color:"blue"}, Profile(null, "click"));
Facebook React

35. este.demos.react.todoApp = este.react.create
render: ->
@div [
este.demos.react.todoList 'items': @state['items']
if @state['items'].length
@p "#{@state['items'].length} items."
@form 'onSubmit': @onFormSubmit, [
@input
'onChange': @onChange
'value': @state['text']
@button "Add ##{@state['items'].length + 1}"
]
]
Facebook React in Este.js

36. Angular/Ember vs. React
<HTML> vs. code()

37. Angular/Ember vs. React
Declarative programming doesn't work. Sooner or
later, all declarative languages ended up Turing-
complete, even HTML+CSS.

38. Separating your markup and logic, that’s not real
separation of concerns. That’s separation of
technologies.
React Great Idea

39. Angular vs. React
server render ready*
SVG/VML/Canvas render ready
Wolfenstein render ready**
* no, Phantom.js is not a solution, it's hideous hack
** www.petehunt.net/wolfenstein3D-react/wlf3d.html

40. React/Angular + Backbone
separate model from view

41. Clean Code and Architecture

42. The Fewer Magic the Better
explicit code over clever code

43. How to Structure App?
By features. Always.

44. /controllers
/directives
/services
/filters
/views
/enumerations
/classes
/wtf's?
Wrong

45. /users
/products
/orders
/controller.js
/model.js
/collection.js
/process.js
/delegate.js
Good

46. Ensure you have a good style,
good source code style.
JSHint, Coffeelint,
Closure Lint (for code style nacist)

47. SOLID Homework
Single responsibility, Open-closed, Liskov substitution,
Interface segregation and Dependency inversion.
en.wikipedia.org/wiki/SOLID_(object-oriented_design)
cleancoders.com

48. MVC
man versus controller

49. Separated Model
Always.

50. Componentization
"The secret to building large apps is never build
large apps. Break your application into small pieces.
Then, assemble those testable, bite-sized pieces
into your big application." Justin Meyer

51. Components or Views?

52. Dependency Injection
or as it's also known, passing arguments

53. Service Locator
code coupling FML

54. How to test this?
function fire() {
Wolf.sound.play();
...
}

55. Is sound instance ready?
function fire() {
Wolf.sound.play();
...
}

56. Better.
function fire() {
this.sound.play();
...
}

57. Fine Service Locator
code coupling FTW!

58. // side effects free
Math.abs x
// intentionally coupled code
new Coordinate x, y
// constants
Math.PI
Fine Service Locators

59. Angular developers can check Facebook now.
App Logic and App Wiring
Separation

60. Good Infrastructure
package management, module loader, source code
linter, task runner

61. Require.js, Bower, Component.io, Grunt.js, Browserify,
ECMAScript 6 modules… etc.
Good Infrastructure

62. Unit Tests
Why and How.

63. Why to Write Unit Tests?
If you don't know why, don't write them!

64. How to Structure Unit Tests
Arrange, Act, Assert.

65. Human
sorry, no patterns for that

66. Except…
Don't cheat and have fun.

67. Thank you
daniel.steigerwald.cz