Introduction to HTML5

© Copyright SELA software & Education Labs Ltd. | 14-18 Baruch Hirsch St Bnei Brak, 51202 Israel | www.selagroup.com
SELA DEVELOPER PRACTICE
December 20-25, 2013
© Copyright SELA software & Education Labs Ltd. 14-18 Baruch Hirsch St.Bnei Brak 51202 Israel
www.sela.co.il
Gil Fink
Introduction to HTML5

Agenda
What is HTML5?
The New Elements
HTML5 JavaScript APIs
CSS3
Q&A
Summary

What is HTML5?
HTML5 ~= HTML + CSS3 + JavaScript API
The future of the web
Still under development
A lot of features supported by modern browsers

Why to use HTML5?
Accessibility
Searchability
Interoperability
Many new
HTML elements and attributes
JavaScript APIs and improved capabilities
CSS capabilities

What’s Under The HTML5
Umbrella?

Structural Elements
No need for div elements all over the place
New ways to mean what you actually meant to
mean
HTML 4 HTML 5

Main Structural Elements
And More
DescriptionElement
Defines an article (for example within a section)Article
Footer elements contain information about their containing
element: who wrote it, copyright, etc.
Footer
The page header shown on the page, not the same as <head>Header
Collection of links to other pagesNav
A part or chapter in a book, or essentially the content body of the
page
Section

Inline Semantic Elements
DescriptionElement
Defines marked textMark
Represents a scalar gauge providing a measurement within a
known range, or a fractional value
Meter
Represents the completion progress of a taskProgress
Represents the result of a calculationOutput
Represents a specific moment in timeTime

New Input Types
Types
Email
Url
Tel
Number
Range
Search
Color
Date pickers (date,
month, week, time,
datetime, datetime-
local)

New Attributes
DescriptionAttribute
Accepted min and max valuesMin, Max
Related to file input type, allows selection of multiple filesMultiple
Specifies a pattern used to validate an input fieldPattern
A short hint intended to aid the user with data entryPlaceholder
Boolean attribute to indicate that the element is requiredRequired
Limits allowed values, thus indicating the granularity requiredStep
And many more

HTML5 <video> Element
Enables to play video natively in the browser
Video can be composited with anything else on the page
HTML content, images, SVG graphics
Include standard codecs like: h.264, ogg and webm
Hardware accelerated, GPU-based decoding in most of the browsers
<video src="video.mp4" id="videoTag" width="640px" height="360px">


</video>

HTML5 <audio> Element
Enables to play audio natively in the browser
Industry-standard MP3 and AAC audio
Fully scriptable via the DOM
<audio src="audio.mp3" id="audioTag" autoplay controls>


</audio>

Demo: Video and Audio Elements

HTML5 Canvas
A block element that allows developers to draw 2D or
3D graphics using JavaScript
For 3D you use WebGL API
<canvas id="myCanvas" width="200" height="200">
Your browser doesn’t support Canvas, sorry.
</canvas>
<script type="text/javascript">
var example = document.getElementById("myCanvas");
var context = example.getContext("2d");
context.fillStyle = "rgb(255,0,0)";
context.fillRect(30, 30, 50, 50);
</script>

Scalable Vector Graphics
Create and draw 2D vector graphics
Vector images are composed of shapes instead of
pixels
Based on the SVG 1.1 2nd Edition Full specification
Support for:
Full DOM access to SVG elements
Document structure, scripting, styling, paths, shapes,
colors, transforms, gradients, patterns, masking,
clipping, markers, linking and views

2D Vector Graphics
<svg width="400" height="200" xmlns="http://www.w3.org/2000/svg">
<rect fill="red" x="20" y="20" width="100" height="75" />
<rect fill="blue" x="50" y="50" width="100" height="75" />
</svg>

Differences Between Canvas and SVG

Geolocation
Many applications are based on user location
Finding nearby restaurants, fuel stations, etc.
Other applications want to gather information
about user locations for future use
HTML5 introduces a new Geolocation
specification
The user must agree to share his or her location
The browser will get the user’s coordinates and other
location information

Geolocation API
The Geolocation API includes the following main
functions:
getCurrentPosition(success, error, options)
watchId = watchPosition(success, error, options)
clearWatch(watchId)
navigator.geolocation.getCurrentPosition(successCallback, errorCallback,
{ enableHighAccuracy: true,
maximumAge: 600000,
timeout: 0 });

Web Workers
Background workers that run scripts in parallel
with their main page
Independent of any user interface scripts
Allow thread-like operations that include
message-passing mechanisms for coordination
Expected to
Be long-lived
Have a high start-up performance cost
Have high per-instance memory cost

Initializing a Web Worker
<p>Result: <output id="result"></output></p>
<script>
var worker = new Worker('worker.js');
worker.onmessage = function (event) {
document.getElementById('result').
textContent = event.data;
};
</script>

Web Worker Script
What appears in the worker.js from the
previous slide
Use the postMessage function in order to send
messages to the UI thread
var n = 1;
while (n < 10000) {
postMessage(n);
n += 1;
}

Web Sockets
Bidirectional communication channel, over a
single TCP socket
Don’t allow raw access to the underlying
network
Uses the new WebSocket JavaScript object
Can replace long-polling and commet
The Web Sockets protocol RFC:
http://tools.ietf.org/html/rfc6455

Web Sockets – JavaScript API
Use the WebSocket object’s built-in events:
onopen: fired when a web socket has opened
onmessage: fired when a message has been received
onclose: fired when a web socket has been closed
socket.onopen = function() {
console.log(‘Socket Status: ‘ + socket.readyState + ‘ (open)’);
}
var socket = new WebSocket('ws://someURL');
Create a WebSocket object using a URL and a list of
protocols
URL must direct to a Web Sockets server endpoint (ws://)

Other HTML5 APIs
HTML5 includes other APIs that you can
consider.
For example:
Web Notifications – display simple notifications to
the user
File API – exposes sandboxed sections of a user’s local
file system to web applications
IndexedDB – an index database on client-side
And many more

CSS3 - Media Queries
<link href="DoNotDisplay.css" rel="stylesheet"
media="screen and (max-width:1199px)" type=“text/css" />
<link href="DoNotDisplay.css" rel="stylesheet"
media="screen and (min-width:1301px)" type="text/css" />
<link href="Presentation.css" rel="stylesheet"
media="screen and (min-width:1200px) and (max-width: 1300px)"
type="text/css" />

CSS3 Colors & Opacity
CSS3 Color
Alpha color with rgba() and hsla() color functions
Transparency control with the opacity property
CSS3 Backgrounds and Borders
Round corners with the border-radius property
Multiple background images per element
box-shadow property on block elements

Other CSS3 Enhancements
CSS3 include much more:
CSS3 Animations
CSS3 Transformations
CSS3 Fonts
CSS3 Border and Background
CSS3 layouts:
Flexbox
Templating
Multi-Columns
More

HTML5 Integration Strategies
HTML5 is HTML
you’re already most of the way there
Most visitors’ browsers can handle most things
Many strategies can be used to implement:
Lowest common denominator
Vertical slices – target a specific HTML5 functionality
JavaScript ‘Polyfills’ can be used to patch the holes
Using fallbacks strategies

HTML5 Bottom Line
Develop once!
Multiple devices reach Multiple platforms reach

Resources
Session slide deck and demos –
HTML5Rocks - http://www.html5rocks.com
HTML5 Landscape Overview -
http://dret.typepad.com/dretblog/html5-api-
overview.html
My Website – http://www.gilfink.net
Follow me on Twitter – @gilfink

Thank You
Gil Fink
Senior Architect
gilf@sela.co.il
@gilfink
http://www.gilfink.net

Introduction to HTML5

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