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HTML5 Overview

by vijay | Jul 06, 2014 | Category: HTML 5 Tutorial for fresher
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HTML5 Overview

HTML5 is the next major revision of the HTML standard superseding HTML 4.01, XHTML 1.0, and XHTML 1.1. HTML5 is a standard for structuring and presenting content on the World Wide Web.
 

HTML5 is a cooperation between the World Wide Web Consortium (W3C) and the Web Hypertext Application Technology Working Group (WHATWG).

The new standard incorporates features like video playback and drag-and-drop that have been previously dependent on third-party browser plug-ins such as Adobe Flash, Microsoft Silverlight, and Google Gears.

Browser Support:

The latest versions of Apple Safari, Google Chrome, Mozilla Firefox, and Opera all support many HTML5 features and Internet Explorer 9.0 will also have support for some HTML5 functionality.

The mobile web browsers that come pre-installed on iPhones, iPads, and Android phones all have excellent support for HTML5.

New Features:

HTML5 introduces a number of new elements and attributes that helps in building a modern websites. Following are great features introduced in HTML5.
 

New Semantic Elements: These are like <header>, <footer>, and <section>.

Forms 2.0: Improvements to HTML web forms where new attributes have been introduced for <input> tag.
 

Persistent Local Storage: To achieve without resorting to third-party plugins.

WebSocket : A a next-generation bidirectional communication technology for web applications.
 

Server-Sent Events: HTML5 introduces events which flow from web server to the web browsers and they are called Server-Sent Events (SSE).

Canvas: This supports a two-dimensional drawing surface that you can program with JavaScript.

Audio & Video: You can embed audio or video on your web pages without resorting to third-party plugins.

Geolocation: Now visitors can choose to share their physical location with your web application.

Microdata: This lets you create your own vocabularies beyond HTML5 and extend your web pages with custom semantics.

Drag and drop: Drag and drop the items from one location to another location on a the same webpage.

Backward Compatibility

HTML5 is designed, as much as possible, to be backward compatible with existing web browsers. New features build on existing features and allow you to provide fallback content for older browsers.

The HTML 5 language has a "custom" HTML syntax that is compatible with HTML 4 and XHTML1 documents published on the Web, but is not compatible with the more esoteric SGML features of HTML 4.

HTML 5 does not have the same syntax rules as XHTML where we needed lower case tag names, quoting our attributes,an attribute had to have a value and to close all empty elements.
 

But HTML5 is coming with lots of flexibility and would support the followings:

Uppercase tag names.

Quotes are optional for attributes.

Attribute values are optional.

Closing empty elements are optional.

The DOCTYPE:

DOCTYPEs in older versions of HTML were longer because the HTML language was SGML based and therefore required a reference to a DTD.

HTML 5 authors would use simple syntax to specify DOCTYPE as follows:

<!DOCTYPE html>

 

All the above syntax is case-insensitive.

Character Encoding:

HTML 5 authors can use simple syntax to specify Character Encoding as follows:

<meta charset="UTF-8">

 

All the above syntax is case-insensitive.

The <script> tag:

It's common practice to add a type attribute with a value of "text/javascript" to script elements as follows:

<script type="text/javascript" src="scriptfile.js"></script>

 

HTML 5 removes extra information required and you can use simply following syntax:

<script src="scriptfile.js"></script>

 

The <link> tag:

So far you were writing <link> as follows:

<link rel="stylesheet" type="text/css" href="stylefile.css">

 

HTML 5 removes extra information required and you can use simply following syntax:

<link rel="stylesheet" href="stylefile.css">

 

HTML5 Elements:

HTML5 elements are marked up using start tags and end tags. Tags are delimited using angle brackets with the tag name in between.

The difference between start tags and end tags is that the latter includes a slash before the tag name.

Following is the example of an HTML5 element:

<p>...</p>

 

 

HTML5 tag names are case insensitive and may be written in all uppercase or mixed case, although the most common convention is to stick with lowercase.

Most of the elements contain some content like <p>...</p> contains a paragrap. Some elements, however, are forbidden from containing any content at all and these are known as void elements. For example, br, hr, link and meta etc.

HTML5 Attributes:

Elements may contain attributes that are used to set various properties of an element.

Some attributes are defined globally and can be used on any element, while others are defined for specific elements only. All attributes have a name and a value and look like as shown below in the example.
 

Following is the example of an HTML5 attributes which illustrates how to mark up a div element with an attribute named class using a value of "example":

<div Class="example">...</div>

 


Attributes may only be specified within start tags and must never be used in end tags.

HTML5 attributes are case insensitive and may be written in all uppercase or mixed case, although the most common convention is to stick with lowercase.

HTML5 Document:

The following tags have been introduced for better structure:

section: This tag represents a generic document or application section. It can be used together with h1-h6 to indicate the document structure.

article: This tag represents an independent piece of content of a document, such as a blog entry or newspaper article.

aside: This tag represents a piece of content that is only slightly related to the rest of the page.

header: This tag represents the header of a section.

footer: This tag represents a footer for a section and can contain information about the author, copyright information, et cetera.

nav: This tag represents a section of the document intended for navigation.

dialog: This tag can be used to mark up a conversation.

figure: This tag can be used to associate a caption together with some embedded content, such as a graphic or video.

The markup for an HTM 5 document would look like the following:

<!DOCTYPE html>

<html>

<head>

   <meta charset="utf-8">

   <title>...</title>

</head>

<body>

  <header>...</header>

  <nav>...</nav>

  <article>

    <section>

      ...

    </section>

  </article>

  <aside>...</aside>

  <footer>...</footer>

</body>

 

As explained in previous chapter, elements may contain attributes that are used to set various properties of an element.

Some attributes are defined globally and can be used on any element, while others are defined for specific elements only. All attributes have a name and a value and look like as shown below in the example.

 

Following is the example of an HTML5 attributes which illustrates how to mark up a div element with an attribute named class using a value of "example":

<div class="example">...</div>

 

 

Attributes may only be specified within start tags and must never be used in end tags.

HTML5 attributes are case insensitive and may be written in all uppercase or mixed case, although the most common convention is to stick with lowercase.

Standard Attributes:

The attributes listed below are supported by almost all the HTML 5 tags.

Attribute

Options

Function

accesskey

User Defined

Specifies a keyboard shortcut to access an element.

align

right, left, center

Horizontally aligns tags

background

URL

Places an background image behind an element

bgcolor

numeric, hexidecimal, RGB values

Places a background color behind an element

class

User Defined

Classifies an element for use with Cascading Style Sheets.

contenteditable

true, false

Specifies if the user can edit the element's content or not.

contextmenu

Menu id

Specifies the context menu for an element.

data-XXXX

User Defined

Custom attributes. Authors of a HTML document can define their own attributes. Must start with "data-".

draggable

true,false, auto

Specifies whether or not a user is allowed to drag an element.

height

Numeric Value

Specifies the height of tables, images, or table cells.

hidden

hidden

Specifies whether element should be visible or not.

id

User Defined

Names an element for use with Cascading Style Sheets.

item

List of elements

Used to group elements.

itemprop

List of items

Used to group items.

spellcheck

true, false

Specifies if the element must have it's spelling or grammar checked.

style

CSS Style sheet

Specifies an inline style for an element.

subject

User define id

Specifies the element's corresponding item.

tabindex

Tab number

Specifies the tab order of an element.

title

User Defined

"Pop-up" title for your elements.

valign

top, middle, bottom

Vertically aligns tags within an HTML element.

width

Numeric Value

Specifies the width of tables, images, or table cells.

Custom Attributes:

A new feature being introduced in HTML 5 is the addition of custom data attributes.

A custom data attribute starts with data- and would be named based on your requirement. Following is the simple example:

<div class="example" data-subject="physics" data-level="complex">

...

</div>

 

The above will be perfectly valid HTML5 with two custom attributes called data-subject and data-level. You would be able to get the values of these attributes using JavaScript APIs or CSS in similar way as you get for standard attributes.

HTML5 Events

When a user visit your website, they do things like click on text and images and given links, hover over things etc. These are examples of what JavaScript calls events.

We can write our event handlers in Javascript or vbscript and you can specify these event handlers as a value of event tag attribute. The HTML5 specification defines various event attributes as listed below:

There are following attributes which can be used to trigger any javascript or vbscript code given as value, when there is any event occurs for any HTM5 element.

We would cover element specific events while discussing those elements in detail in subsequent chapters.

 

Attribute

Value

Description

offline

script

Triggers when the document goes offline

onabort

script

Triggers on an abort event

onafterprint

script

Triggers after the document is printed

onbeforeonload

script

Triggers before the document loads

onbeforeprint

script

Triggers before the document is printed

onblur

script

Triggers when the window loses focus

oncanplay

script

Triggers when media can start play, but might has to stop for buffering

oncanplaythrough

script

Triggers when media can be played to the end, without stopping for buffering

onchange

script

Triggers when an element changes

onclick

script

Triggers on a mouse click

oncontextmenu

script

Triggers when a context menu is triggered

ondblclick

script

Triggers on a mouse double-click

ondrag

script

Triggers when an element is dragged

ondragend

script

Triggers at the end of a drag operation

ondragenter

script

Triggers when an element has been dragged to a valid drop target

ondragleave

script

Triggers when an element leaves a valid drop target

ondragover

script

Triggers when an element is being dragged over a valid drop target

ondragstart

script

Triggers at the start of a drag operation

ondrop

script

Triggers when dragged element is being dropped

ondurationchange

script

Triggers when the length of the media is changed

onemptied

script

Triggers when a media resource element suddenly becomes empty.

onended

script

Triggers when media has reach the end

onerror

script

Triggers when an error occur

onfocus

script

Triggers when the window gets focus

onformchange

script

Triggers when a form changes

onforminput

script

Triggers when a form gets user input

onhaschange

script

Triggers when the document has change

oninput

script

Triggers when an element gets user input

oninvalid

script

Triggers when an element is invalid

onkeydown

script

Triggers when a key is pressed

onkeypress

script

Triggers when a key is pressed and released

onkeyup

script

Triggers when a key is released

onload

script

Triggers when the document loads

onloadeddata

script

Triggers when media data is loaded

onloadedmetadata

script

Triggers when the duration and other media data of a media element is loaded

onloadstart

script

Triggers when the browser starts to load the media data

onmessage

script

Triggers when the message is triggered

onmousedown

script

Triggers when a mouse button is pressed

onmousemove

script

Triggers when the mouse pointer moves

onmouseout

script

Triggers when the mouse pointer moves out of an element

onmouseover

script

Triggers when the mouse pointer moves over an element

onmouseup

script

Triggers when a mouse button is released

onmousewheel

script

Triggers when the mouse wheel is being rotated

onoffline

script

Triggers when the document goes offline

onoine

script

Triggers when the document comes online

ononline

script

Triggers when the document comes online

onpagehide

script

Triggers when the window is hidden

onpageshow

script

Triggers when the window becomes visible

onpause

script

Triggers when media data is paused

onplay

script

Triggers when media data is going to start playing

onplaying

script

Triggers when media data has start playing

onpopstate

script

Triggers when the window's history changes

onprogress

script

Triggers when the browser is fetching the media data

onratechange

script

Triggers when the media data's playing rate has changed

onreadystatechange

script

Triggers when the ready-state changes

onredo

script

Triggers when the document performs a redo

onresize

script

Triggers when the window is resized

onscroll

script

Triggers when an element's scrollbar is being scrolled

onseeked

script

Triggers when a media element's seeking attribute is no longer true, and the seeking has ended

onseeking

script

Triggers when a media element's seeking attribute is true, and the seeking has begun

onselect

script

Triggers when an element is selected

onstalled

script

Triggers when there is an error in fetching media data

onstorage

script

Triggers when a document loads

onsubmit

script

Triggers when a form is submitted

onsuspend

script

Triggers when the browser has been fetching media data, but stopped before the entire media file was fetched

ontimeupdate

script

Triggers when media changes its playing position

onundo

script

Triggers when a document performs an undo

onunload

script

Triggers when the user leaves the document

onvolumechange

script

Triggers when media changes the volume, also when volume is set to "mute"

onwaiting

script

Triggers when media has stopped playing, but is expected to resume

 

HTML5 - Web Forms 2.0

Web Forms 2.0 is an extension to the forms features found in HTML4. Form elements and attributes in HTML5 provide a greater degree of semantic mark-up than HTML4 and remove a great deal of the need for tedious scripting and styling that was required in HTML4.

The <input> element in HTML4

HTML4 input elements use the type attribute to specify the data type.HTML4 provides following types:

Type

Description

text

A free-form text field, nominally free of line breaks.

password

A free-form text field for sensitive information, nominally free of line breaks.

checkbox

A set of zero or more values from a predefined list.

radio

An enumerated value.

submit

A free form of button initiates form submission.

file

An arbitrary file with a MIME type and optionally a file name.

image

A coordinate, relative to a particular image's size, with the extra semantic that it must be the last value selected and initiates form submission.

hidden

An arbitrary string that is not normally displayed to the user.

select

An enumerated value, much like the radio type.

textarea

A free-form text field, nominally with no line break restrictions.

button

A free form of button which can initiates any event related to button.

 

Following is the simple example of using labels, radio buttons, and submit buttons:

...

<form action="http://example.com/cgiscript.pl" method="post">

    <p>

    <label for="firstname">first name: </label>

              <input type="text" id="firstname"><br />

    <label for="lastname">last name: </label>

              <input type="text" id="lastname"><br />

    <label for="email">email: </label>

              <input type="text" id="email"><br>

    <input type="radio" name="sex" value="male"> Male<br>

    <input type="radio" name="sex" value="female"> Female<br>

    <input type="submit" value="send"> <input type="reset">

    </p>

 </form>

 ...

 

The <input> element in HTML5

Apart from the above mentioned attributes, HTML5 input elements introduced sevral new values for the type attribute. These are listed below.

NOTE: Try all the following example using latest version of Opera browser.

Type

Description

datetime

A date and time (year, month, day, hour, minute, second, fractions of a second) encoded according to ISO 8601 with the time zone set to UTC.

datetime-local

A date and time (year, month, day, hour, minute, second, fractions of a second) encoded according to ISO 8601, with no time zone information.

date

A date (year, month, day) encoded according to ISO 8601.

month

A date consisting of a year and a month encoded according to ISO 8601.

week

A date consisting of a year and a week number encoded according to ISO 8601.

time

A time (hour, minute, seconds, fractional seconds) encoded according to ISO 8601.

number

This accepts only numerical value. The step attribute specifies the precision, defaulting to 1.

range

The range type is used for input fields that should contain a value from a range of numbers.

email

This accepts only email value. This type is used for input fields that should contain an e-mail address. If you try to submit a simple text, it forces to enter only email address in email@example.com format.

url

This accepts only URL value. This type is used for input fields that should contain a URL address. If you try to submit a simple text, it forces to enter only URL address either in http://www.example.com format or in http://example.com format.

The <output> element

HTML5 introduced a new element <output> which is used to represent the result of different types of output, such as output written by a script.

You can use the for attribute to specify a relationship between the output element and other elements in the document that affected the calculation (for example, as inputs or parameters). The value of the for attribute is a space-separated list of IDs of other elements.

The placeholder attribute

HTML5 introduced a new attribute called placeholder. This attribute on <input> and <textarea> elements provides a hint to the user of what can be entered in the field. The placeholder text must not contain carriage returns or line-feeds.

Here is the simple syntax for placeholder attribute:

<input type="text" name="search" placeholder="search the web"/>

 

This attribute is supported by latest versions of Mozilla, Safari and Chrome browsers only.

The autofocus attribute

This is a simple one-step pattern, easily programmed in JavaScript at the time of document load, automatically focus one particular form field.

HTML5 introduced a new attribute called autofocus which would be used as follows:

<input type="text" name="search" autofocus/>

 

This attribute is supported by latest versions of Mozilla, Safari and Crome browsers only.


 

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