HTML5 for the Silverlight Guy

HTML5 for the
Silverlight Guy
An introduction to “Serious”
development on the Web Platform
David Padbury
http://davidpadbury.com
@davidpadbury

So, this whole Silverlight vs HTML5 has
been a little controversial...

“Microsoft execs said tonight ... allow them to create Windows 8
applications in HTML and/or JavaScript.
Sinofsky and others didn’t mention Silverlight or XNA at all.”
http://www.zdnet.com/blog/microsoft/windows-8-more-than-just-windows-phone-on-your-pc/9592?tag=mantle_skin;content

http://forums.silverlight.net/forums/p/230502/562113.aspx#562081

“...they want us to write freaking javascript. Really!?”

“HTML5??? Microsoft isn't eating their own dogfood, they're eating their own vomit.”

“It may just be a very cool thing if they are brewing a way to utilize html5 + javascript
**without us having to mess with javascript** (exactly what ASP.NET does on the client side)”

“At this point html5/js is a horrible development platform... I have not seen a single
project developed purely in html/js.”

“we get Html and JavaScarriness in place of the beauty we know”

“Seriously, who decided that we should start basing all of our computing around the
most abysmally slow language!?”

“Contrary to popular belief, HTML 5 is not ready yet.”

“there is no way you would write a trading application in HTML5 and javascript”

Javascript may be the WORST language ever used to write "applications". It's a joke.

“You can’t write serious applications in
HTML and JavaScript.”

There’s lots of cool HTML5 demos out there

But how do I build a rich front end application?

That’s what I’m going to (try) helping you understand today.

But ﬁrst.

Silverlight is not dead.

Evaluate HTML5 the same way you would anything else.

It’s good at some things, it sucks at others.

Although this is the web,
forget your server side web programming experience.

ASP.NET, Rails, Grails, PHP

Well, not entirely but you’ll see where I’m going.
I’m trying to be dramatic.

Writing complex front-end in HTML+JavaScript
has more in common with WPF/SL than ASP.NET

For you guys, this is a good thing.

Application is built from modules
Modules are decoupled from each other
Code is easy to test
Runs on Desktop, RIA, and (windows 7) Phone

Today’s Talk

JavaScript
JavaScript Modules
Module Organization
Views as Modules Decoupling and Testing
Event Aggregator/PubSub
Unit Testing View Modules
CSS
CSS Compilers
Platform Consistency
HTML5 Everywhere
We’re going to talk about the Plugins
boring bits of HTML5 Devices

“JavaScript doesn’t suck.
You’re just doing it wrong.”
- Douglas Crockford
(father of JSON and JSLint, author of The Good Parts)

The tone’s a little harsh, but he has a point.
Despite looking similar to C#, JavaScript is a very different language.

JavaScript is a very simple language
If you can learn C#, you can cope with JavaScript.

There are three things you have to learn to
be a great JavaScript developer.

First Class Functions

Prototypes

Context

First Class Functions
function createCounter() {
var count = 0;

return function() {
return count++;
};
}

var counter1 = createCounter(),
counter2 = createCounter();

console.log( counter1() ); // 0

Context
Or, which this is this?

var david = {
name: 'David',
sayHi: function() {
console.log("Hi, I'm " + this.name);
}
};

david.sayHi(); // Hi, I'm David
// obj.fn() is eqv to obj.fn.call(obj)

david.sayHi.call({name:'Colleen'});
// Hi, I'm Colleen

Prototypes

function Person(name) {
this.name = name;
}

Person.prototype.sayHi = function() {
console.log("Hi, I'm " + this.name);
};

var david = new Person('David'),
colleen = new Person('Colleen');

david.sayHi(); // Hi, I'm David
colleen.sayHi(); // Hi, I'm Colleen

console.log( david.sayHi === colleen.sayHi ); // true

Some older bits aren’t great...

strict mode keeps us on the Good Parts

Start a ﬁle with ‘use strict’;

'use strict';

alert( "I'm in strict mode." );

Or start a function with ‘use strict’;

(function() {
'use strict';

alert("I'm in strict mode!");
})();

(function() {
globalVariable = 'OOPS!';
})();

console.log(globalVariable);
// OOPS!

(function() {
'use strict';
globalVariable = 'OOPS!';
})();

console.log(globalVariable);

ReferenceError: globalVariable is not defined

var person;

(function() {
person = {
name: 'David',
name: 'Colleen'
};
})();

console.log(person.name);
// Colleen

var person;

(function() {
'use strict';
person = {
name: 'David',
name: 'Colleen'
};
})();

console.log(person.name);

SyntaxError: Duplicate data property in
object literal not allowed in strict mode

(function() {
console.log( 012 + 2 );
})();

(function() {
console.log( 012 + 2 ); // 12?!
})();

(function() {
'use strict';
console.log( 012 + 2 );
})();

SyntaxError: Octal literals are not
allowed in strict mode.

C# has using

Visual Basic has Imports

JavaScript has?

C# has using

Visual Basic has Imports

JavaScript has?
Nothing.

<!DOCTYPE HTML>
<html>
<body>
<script>
// Application goes here...
</script>
</body>
</html>

$(document).ready(function() {
function addSymbol(symbol) {
var row = $('<tr>').append($('<td>').text(symbol));
$('.watches').children().append(row);
}
$('.screen-switcher a').click(function() {
var screen = $(this).attr('data-screen-id');
$('.screens .screen').slideUp('fast', function() {
$('.screens .screen[data-screen=' + screen + ']').slideDown();
});
});
$('.add-symbol').parent('form').submit(function(e) {
e.preventDefault();
var symbol = $('.add-symbol').val();
addSymbol(symbol);
$.ajax('/data/symbol' + symbol, {
completed: function(xhr, data) {
$('<div class="price">')
.text(data.price)
.click(function() {
$('.price .tooltip')
.show('fast', function() {
$(this).text(price);
})
});
}
});
});
$('.sidebar .history').flot({
data: $.ajax('/stock/history', {
data: [1,23,4,5,6],
date: new Date().getTime()
});

Everything is global by default

// lib1.js
function something() {
console.log('foo');
}

// lib2.js
function something() {
console.log('bar');
}

<script src="lib1.js"></script>
<script src="lib2.js"></script>
<script>
something(); // bar
</script>

The patterns and tools and practices that will
form the foundation of Modern JavaScript are
going to have to come from outside
implementations of the language itself
- Rebecca Murphey

Using simple JavaScript constructs we can emulate many
traditional organization techniques

(function(lab49) {

function privateAdder(n1, n2) {
return n1 + n2;
}

lab49.add = function(n1, n2) {
return privateAdder(n1, n2);
};

})(window.lab49 = window.lab49 || {});

lab49.add(2, 3);

Known as the Module Pattern
http://blog.davidpadbury.com/2011/08/21/javascript-modules/

Modules have evolved into standard patterns with
tooling to help loading and packaging.

Asynchronous Module Deﬁnition
(Commonly known as AMD)

https://github.com/amdjs/amdjs-api/wiki/AMD

define for creating a module deﬁnition.

require to ask for a module instance.

define('calculator', function() {
return {
add: function(n1, n2) {
return n1 + n2;
}
}; Callback so modules can be loaded asynchronously
});

require(['calculator'], function(calculator) {
console.log( calculator.add(1, 2) ); // 3
});

define('math/adder', function() {
return {
return n1 + n2;
} Specify modules this module depends on
}
});

define('math/calculator', ['./adder'], function(adder) {
return {
return adder.add(n1, n2);
}
}; Loader passes instances of them
});

Loaders can assume module names from ﬁles
// math/adder.js
define(function() {
return {
return n1 + n2;
}
}
});

// math/calculator.js
define(['./adder'], function(adder) {
return {
return adder.add(n1, n2);
}
};
});

AMD appears to be winning in how to large JavaScript code bases

There are a number of AMD module loaders
RequireJS, curl.js

Popular libraries are supporting AMD
Dojo, jQuery (as of 1.7)

You can extend how modules are loaded using plugins

text!
i18n!
order!

// views/personView.html
<div>My name is: <span class="name"></span></div>


// views/personView.js
define(['text!./personView.html'], function(tmpl) {
function PersonView(options) {
var el = $(options.el),
Ask for content with the text
name = options.name; plugin and we get a String

el.html(tmpl).find('.name').text(name);
}
return PersonView;
});


// views/personView.js
define(['text!./personView.html'], function(tmpl) {
function PersonView(options) {
var el = $(options.el),
Ask for content with the text
name = options.name; plugin and we get a String

el.html(tmpl).find('.name').text(name);
}
return PersonView;
});

// index.html
<div id="person"></div>
<script>
require(['views/personView'], function(PersonView) {
var personView = new PersonView({
el: $('#person'), name: 'David'
});
});
</script>

This allows us to organize our
applications the way we’re used to

C# JavaScript
(Yep, I know you would’ve guessed...)

Demo
“Controls” with RequireJS

require(['pubsub'], function(PubSub) {
var bus = new PubSub();

bus.sub('say', function(msg) {
console.log('Subscriber 1 says: ' + msg);
});

bus.sub('say', function(msg) {
console.log('Subscriber 2 says: ' + msg);
});

bus.pub('say', 'Nope!');
// Subscriber 1 says: Nope!
// Subscriber 2 says: Nope!
});

“Dictionary” to hold topic to
define('pubsub', function() { list of subscriptions
function PubSub() {
this.subs = {};
}
Create topic list if none exists
PubSub.prototype = {
sub: function(topic, fn) {
var topicSubs = (this.subs[topic] = this.subs[topic] || []);
topicSubs.push(fn);
},
pub: function(topic, data) {
var topicSubs = this.subs[topic] || [];
topicSubs.forEach(function(fn) {
fn(data);
});
}
}; Call each subscriber for topic
return PubSub;
});

(This is is a horribly crap implementation - DON’T EVER USE IT!)

The ease of Unit Testing is one of the
biggest plus points for JavaScript

There’s a lot less ﬁghting the compiler.
Which is handy, as they’re useful as there is no compiler.

There is a large number of unit testing libraries and frameworks
QUnit (of jQuery fame)
Jasmine (BDD’ish)

describe('Calculator', function() {
var calculator;

beforeEach(function() {
calculator = require('calculator');
});

it('should add two numbers correctly', function() {
expect(calculator.add(2, 3)).toEqual(5);
});
});

Demo
Unit Testing jQuery and mocks

CSS is wonderfully simple.

selector {
property: value;
}

But sometimes it feels a little too simple.

Take it up a level - CSS Compilers

SASS
WebWorkbench (VS), SassAndCoffee (ASP.NET), Ruby

LESS
WebWorkbench (VS), dotless (ASP.NET), Java, Ruby, Node, JavaScript

Stylus
Node

Repetition in CSS sucks

.content-navigation {
border-color: #3bbfce;
}

.border {
border-color: #3bbfce;
}

SASS gives us variables

$blue: #3bbfce;
.content-navigation {
.content-navigation { border-color: #3bbfce;
border-color: $blue; }
}
.border {
.border { border-color: #3bbfce;
border-color: $blue; }
}
CSS
SASS

Having to repeat selector paths sucks

header { background-color: blue; }

header a { font-weight: normal; }

header a:hover { font-weight: bold; }

SASS gives us nesting
header {
background-color: blue;

a {
font-weight: normal;
&:hover { SASS
font-weight: bold;
}
}
}

header { background-color: blue; }

header a { font-weight: normal; } CSS
header a:hover { font-weight: bold; }

Having to repeat vendor preﬁxes sucks

#container {
-ms-box-flex: 1;
-o-box-flex: 1;
-webkit-box-flex: 1;
-moz-box-flex: 1;
box-flex: 1;
}

SASS gives us mixins

@mixin box-flex($flex) {
-ms-box-flex: $flex;
-o-box-flex: $flex; #container {
-webkit-box-flex: $flex; -ms-box-flex: 1;
-ms-box-flex: $flex; -o-box-flex: 1;
box-flex: $flex; -webkit-box-flex: 1;
} -moz-box-flex: 1;
box-flex: 1;
#container { }
@include box-flex(1);
} CSS

SASS

Platform Consistency

Or, everyone else’s browser sucks.

Writing an app for a single
browser is easy.

Writing a single app for multiple
browsers can be hard.

Just ask it

function hasCssProp(prop) {
var el = document.createElement('div'),
style = el.style;

return typeof style[prop] == 'string';
}

// In IE9, Chrome, Firefox, etc...
hasCssProp('borderRadius'); // true

// In IE6, IE7, IE8, etc...
hasCssProp('borderRadius'); // false

Demo
Modernizr + SASS + CSS3 Hawtness + CSS2 Not-so-hawtness

The elephant in the room...

“But my company is all IE6...”

border-radius: 8px;
box-shadow: #666 0px 2px 3px;
background: linear-gradient(#eeff99, #66ee33);
behavior: url(/PIE.htc);

http://css3pie.com/

You can fake a lot.

But honestly, it sucks.

Accept reality.

Chrome Frame - a plugin with beneﬁts

System Admin Compatible
Roll out with MSI

Control with Group Policy Settings

User Installable
Just include a script in page

Non-admin installs supported

Keep IE
Sites have to explicitly opt-in to Chrome Frame

Sites depending on IE6/7 stay in IE6/7
http://www.google.com/chromeframe

Running the same application - http://html5trader.com

Internet Explorer 6 iPhone

Running the same application - http://html5trader.com

“This HTML5 stuff would be ﬁne,
if only there was decent tooling...”

Visual Studio 11 is looking much better...

http://blogs.msdn.com/b/webdevtools/archive/2011/09/15/new-javascript-editing-features-
for-web-development-in-visual-studio-11-developer-preview.aspx

We use Intellisense to
‘Explore’ and ‘Discover’

http://www.ﬂickr.com/photos/gemmabou/4622213880/

With modern browsers we can easily and
quickly explore our code at runtime

// Getter
$('#test').css('backgroundColor');

// Setter
$('#test').css('backgroundColor', 'red');

// Bigger setter
$('#test').css({
backgroundColor: 'red'
});

Static analysis for JavaScript

function add(a, b, c) {
return a + b;
}

var person = {
name: 'David',
company: 'Lab49',
};

function createPerson(name) {
return
{
name: name
};
}

There’s tons of other tools....

Automation Testing
Validators
Performance
Debuggers
Proﬁlers
Designers

On many other platforms...

.NET
Java
Ruby
Python
Node

It is not Silverlight vs HTML5
They’re both valid options with different pros and cons

You guys are experts in building front-end applications.

Although the code looks a little different...

The patterns, techniques and good
practices are the same.

Be Conﬁdent
Be Fearless
(and be sensible)

Hang on,

You went an entire talk to a Silverlight
audience and didn’t once mention MVVM?

Yep - although you can reuse a lot of knowledge, don’t try to do everything exactly the same.
I encourage you to start with the simplest thing and build from there.

You didn’t cover ...!?
Acceptance Testing
CoffeeScript
Underscore
Templates Server Tools IOC
jQuery JavaScriptMVC

HTML5 Boiler Plate KnockOut Flow Control

Project Silk BDD
Backbone
ECMAScript 6 ASP.NET Integration

jQuery UI
Promises Goldﬁsh
Script Loaders

Dec 6th
RequireJS 1.0

Callbacks, Promises and Coroutines (on my!)

The NY HTML5 Application Developers Group

Dec 6th
RequireJS 1.0

Callbacks, Promises and Coroutines (on my!)

http://www.meetup.com/html5-app-developers

New York .NET Meetup

http://www.meetup.com/NY-Dotnet

// Thanks for listening!

return;

HTML5 for the Silverlight Guy

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