intr to html & xhtml
TRANSCRIPT
Introduction to HTML &Introduction to HTML &XHTMLXHTML
IntroductionIntroduction
Web developers view web pages as documents that must be created according to authoring and development guidelines
Web developers use HTML or XHTML to write code of a web page
Web browsers have a built-in interpreter to render the results of the code in its window
The World Wide WebThe World Wide Web Definitions
HTML The HyperText Markup Language The language used to structure text-based information
in a document by denoting certain text as headings, paragraphs, lists,
etc — and to supplement that text with interactive forms, embedded images, and other multimedia objects
XHTML The eXtensible HyperText Markup Language XHTML consists of all the elements in HTML 4.01
combined with the syntax of XML. Allows users to define their own “tags” for defining
structure, layout, etc.
Content of Web PagesContent of Web Pages
A web site may contain a combination of 13 standard elements:
Text Sound
Lists Video
Hyperlinks Tables
Colour Layers
Graphics Frames
Images Forms
Image Maps
Content of Web PagesContent of Web Pages
The content of a web site can be classified as: Static content – does not change regularly e.g.
personal and professional web sites Dynamic content – changes regularly e.g.,
newspaper web sites, weather report sites…
Authoring of Web PagesAuthoring of Web Pages After a web page layout is designed, one needs to use
HTML/XHTML code to implement the design Introduction to XHTML
Syntax Document Tags Authoring tools Text formatting Special characters Hyperlinks Lists Meta Data Colours Audio & Video
XHTML SyntaxXHTML Syntax XHTML uses tags that are enclosed in brackets < >
XHTML content is contained between tags
Tags and content form an XHTML element
Generic element form: <start-tag> content <end-tag>
Start and end tags have the same name, end tag has a ‘/’ before it: <b>This is BOLD</b>
XHTML tags can be nested according to the “first open, last closed” rule: <b><i>bold and italic</i></b>
XHTML SyntaxXHTML Syntax XHTML rules
Tags must be closed XHTML is case sensitive Use lower case tags and attribute names, e.g. width=“100%” All attribute values must be double quoted, e.g. “100%” Tags must not overlap (i.e., during nesting) Comments can be used
<!-- This text is a comment -->
Do not use obsolete (deprecated) tags Browsers ignore misspelled tags (and many other things!)
Document TagsDocument TagsThe tags that make up the framework of a typical XHTML document include the following:
Document type definition (DTD) tag – DOCTYPE<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
Describes (to web browsers) what type/version of (x)html is used
Specifies rules that apply to the markup of documents
Used for document syntax validation (e.g. strict) and for web browser to process document in proper “parsing” mode (impacts on consistency and speed of display)
An XHTML document is validated against a Document Type Definition.
Top-level tag, generally <html> Tag indicates the beginning and /end of an XHTML document
Sample XHTML Document StructureSample XHTML Document Structure<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<HTML> <HEAD> <TITLE> New Document </TITLE> <META NAME="Author" CONTENT=""> <META NAME="Keywords" CONTENT=""> <META NAME="Description" CONTENT=""> </HEAD>
<BODY> webpage content goes here! </BODY></HTML>
Minimal XHTML DocumentMinimal XHTML Document
<!DOCTYPE ….><html>
<head>…..
</head>
<body>
<p>
…….
</p></body>
</html>
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HTML Document StructureHTML Document Structure
<html><head>
<title>HTML Document Structure</title> <meta name=“author” content=“Andrea Curley” />
</head><body>
all web page content goes here</body>
</html>
Document Tags - HeaderDocument Tags - Header
Header section, delimited by <head> tags Provides extra information about the document Serves as a container for styles, global scripts, etc. The main tags used in this section are:
<title> - specifies the document title <meta> - provides information to search engines <style> - declares general & local styles for the document <script> - declares any scripting information
Meta TagsMeta Tags
Web pages are designed for surfers and surf engines
The <meta> tag increases the chances of page indexing
Meta data refers to data about XHTML document rather than the document content
Browsers do not render meta data
Search engines use it for indexing and ranking the page hits in a given search
Some attributes of this tag are name, content, http-equiv, etc.
Meta TagsMeta Tags
Most often the meta element is used to provide information that is relevant to browsers or search engines like describing the content of your document.
<meta name=“keywords” content=“open, source, PHP, programming, code” />
When a search engine indexes the page, it includes the extra information -> open, source, etc.
It provides these keywords to search agents requesting them
Amazon’s Meta TagsAmazon’s Meta Tags<meta name="description" content="Low prices on digital cameras,
MP3, LCD TVs, books, music, DVDs, video games, software, home & garden and much, much more. Free delivery on orders over £15." />
<meta name="keywords" content="digital camera, LCD TV, books, DVD, low prices, video games, pc games, software, electronics, home, garden, video, amazon" />
Document Tags - BodyDocument Tags - Body
Body section, delimited by <body> tags Section where visible content appears Content is a series of block tags containing inline
content
How can I write my first web page?How can I write my first web page?
1. Open a text editor e.g., Notepad, Edit Plus
2. Put in code from the HTML Document Structure Slide
3. Save it as Example1.html
4. In web browser (IE/Firefox/Netscape), Select File -> Open Select Example1.html Select OK
Authoring ToolsAuthoring Tools Tools needed to develop a web site:
Editor Graphics program Digital cameras Scanners Audio & video software
Types of editors Text: type in code and view results later -> Bottom-up development HTML: view results as you develop the web page -> top-down
development
Web author must be familiar with both approaches e.g. “EditPlus”, “MacroMedia Dreamweaver”
Text FormattingText Formatting Paragraphs Line breaks Headings Horizontal Rules Block divisions
ParagraphsParagraphs Main textual blocks, delimited by <p> tags
<p>This is a paragraph of text in an XHTML document</p>
This is a paragraph of text in an XHTML document
Line spaces Line spaces automatically automatically insertedinserted
Line breaksLine breaks
Used when you need to break a line prematurely (before the paragraph)
The line break tag is <br /> Need space between “br” and “/” for Netscape
browsers to interpret correctly
Lines - ExampleLines - Example<p>This is a paragraph of text in an XHTML document</p><p>This is a 2nd paragraph of text in an XHTML document</p>
This is a paragraph of text in an XHTML document
This is a 2nd paragraph of text in an XHTML document
<p>This is a paragraph of text in an XHTML document</p><p>This is a 2nd paragraph of text <br /> in an XHTML document</p>
This is a paragraph of text in an XHTML document
This is a 2nd paragraph of text in an XHTML document
HeadingsHeadings There are 6 levels of headings <h1>…..<h6>, the higher
the heading number the smaller the text
<h1> Heading 1</h1>
<h2> Heading 2</h2>
<h3> Heading 3</h3>
<h4> Heading 4</h4>
<h5> Heading 5</h5>
<h6> Heading 6</h6>
Heading 1Heading 1Heading 2Heading 2Heading 3Heading 3Heading 4Heading 4Heading 5Heading 5Heading 6Heading 6
Horizontal RulesHorizontal Rules Horizontal rules appear as lines across the browser screen
- <hr /> use space between “hr” and “/” so Netscape browsers can interpret correctly
Used to separate information visually
A line should be drawn under this text <hr />
A line should be drawn under this text
Block Divisions (div)Block Divisions (div) Sometimes, there is a need to format a large block of text
in a similar fashion but in a way that is different from other blocks in the same document e.g. a quoted block of text could appear in a different style than the text around it - <div>
<div align="center"> Text formatted using div tag
</div>
Text formatted using div tag
Text FormattingText Formatting
TextText
HeadingsHeadings ParagraphsParagraphs Word/CharactersWord/Characters
<h1> largest<h1> largest....<h6> smallest<h6> smallest
<p><p><b> bold<b> bold<i> italic<i> italic<br /> line break<br /> line break<div> acts like a line break<div> acts like a line break
<hr /> line in a web page, <hr /> line in a web page,
HyperlinksHyperlinks Hyperlinks <a> link web pages to each other
A link is a connection from one source to another Hyperlinks create hypertext and is the driving force of the web
Hyperlinks can be used as: inter-document and intra-document links
Links start at the source (visible part) and points to the destination (invisible part)
<a href="http://www.w3schools.com/"> Visit W3Schools! </a>
address of the address of the document to link todocument to link to(invisible)(invisible)
Text to be Text to be be displayed as a hyperlinkbe displayed as a hyperlink(visible)(visible)
HyperlinksHyperlinks The important attributes of the link <a> tag:
href title name charset type rel rev accesskey shape coords
HyperlinksHyperlinks The visible part of the link may have 4 states
Link – is not active and has not been visited Active – target of the link is active in another browser window Visited – target of the link has been previously visited Hover – mouse pointer is over the link
Redirect Example
<html><head>
<meta http-equiv="Refresh" content="5;url=http://www.dit.ie" /></head><body>
<p>Sorry! We have moved! The new URL is: <a href="http://www.dit.ie">www.dit.ie</a></p>
<p>You will be redirected to the new address in five seconds.</p><p>If you see this message for more than 5 seconds, please click on the link above!</p>
</body></html>
Hyperlinks - anchorsHyperlinks - anchors
for “external” link<a href=http://www.dit.ie target=“_blank”> This is the DIT web
site</a>
…for “internal” link<a href=“#Section1”> jump to Section 1</a>
.<a name=“Section1”>Section 1</a>
… for “mail to” link<a href="mailto:[email protected]">email [email protected]</a>
ListsLists
XHTML supports 3 types of lists: Ordered – <ol> Unordered – <ul> Definition – <dl>
Lists may be nested to obtain multiple hierarchy levels
Ordered List - <ol>Ordered List - <ol>
Lists whose elements must appear in a certain order
Such lists usually have their items prefixed with a number or letter
<ol><ol><li>Apples</li><li>Apples</li><li>Bananas</li><li>Bananas</li><li>Coconuts</li><li>Coconuts</li>
</ol></ol>
1.1. ApplesApples2.2. BananasBananas3.3. CoconutsCoconuts
Ordered List - <ol>Ordered List - <ol> How can the numbering style be changed??
Some other style options: decimal lower-roman upper-roman upper-alpha
<ol <ol style=“list-style-type: lower-alpha”style=“list-style-type: lower-alpha”>><li>Apples</li><li>Apples</li><li>Bananas</li><li>Bananas</li><li>Coconuts</li><li>Coconuts</li>
</ol></ol>
a.a. ApplesApplesb.b. BananasBananasc.c. CoconutsCoconuts
Unordered List - <ul>Unordered List - <ul>
Lists whose elements do not have to appear in a numbered order
<ul><ul><li>Apples</li><li>Apples</li><li>Bananas</li><li>Bananas</li><li>Coconuts</li><li>Coconuts</li>
</ul></ul>
• ApplesApples• BananasBananas• CoconutsCoconuts
Unordered List - <ul>Unordered List - <ul> How can the list item marker be changed??
Some other style options: disc circle none
<ul <ul style=“list-style-type: square”style=“list-style-type: square”>><li>Apples</li><li>Apples</li><li>Bananas</li><li>Bananas</li><li>Coconuts</li><li>Coconuts</li>
</ul></ul>
ApplesApplesBananasBananasCoconutsCoconuts
Definition List - <dl>Definition List - <dl> More complex than the other 2 lists due to their
having 2 elements per list item<dl><dl> <dt>Internet Explorer</dt><dt>Internet Explorer</dt> <dd>Developed by Microsoft</dd><dd>Developed by Microsoft</dd> <dt>Netscape</dt><dt>Netscape</dt> <dd>Developed by Netscape</dd><dd>Developed by Netscape</dd> </dl></dl>
Internet ExplorerInternet ExplorerDeveloped by MicrosoftDeveloped by Microsoft
NetscapeNetscapeDeveloped by NetscapeDeveloped by Netscape
Nesting ListsNesting Lists
Lists can be nested of the same or different types
<ul><ul> <li>Send us a letter, including:</li><li>Send us a letter, including:</li> <ol><ol>
<li>Your full name</li><li>Your full name</li><li>Your order number</li><li>Your order number</li><li>Your contact information</li><li>Your contact information</li>
</ol></ol> <li> Use the web form to send an email </li><li> Use the web form to send an email </li></ul></ul>
• Send us a letter, including:Send us a letter, including:1.1. Your full nameYour full name2.2. Your order numberYour order number3.3. You contact informationYou contact information
• Use the web form to send an emailUse the web form to send an email
ColoursColours
Colour is an essential element and greatly improves visualisation
A web author can set colours for background and text
Tags have a color attribute that enables web authors to set colours for different XHTML elements
Colours can be specified using hexadecimal codes for multi-browser consistency Black -> #000000 Red -> #FF0000 Blue -> #0000FF
Colours can be set globally or locally
Audio & Video Audio & Video
XHTML allows authors to incorporate digital audio and videos in a web page Audio formats – AU, WAV, MIDI, AIFF and MP3
Video formats – AVI, QuickTime, MPEG and MJPEG
A surfer must have the right hardware and software to be able to play multimedia content of the web page
<embed> tag causes a control panel to be displayed for audio and video files in a web page
Attributes used are src, width and height, volume, autostart, loop and hidden
Audio & Video Audio & Video
<embed src="music.mp3" width="145" height="60" volume="70"> </embed>
Reference Reference
Steven M. Schafer (2005), HTML, CSS, JavaScript, Perl, and PHP Programmer's Reference, Hungry Minds Inc,U.S.
Dan Cederholm (2005), Bulletproof Web Design: Improving Flexibility and Protecting Against Worst-Case Scenarios with XHTML and CSS, New Riders.
Ibrahim Zeid (2004), Mastering the Internet, XHTML, and Javascript