Transcript 2.2 - DIT
Introduction to HTML & XHTML 15th February Introduction to HTML & XHTML Introduction to HTML Introduction to XHTML Introduction Web developers views a web page as a document 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 a code in its window The World Wide Web Definitions HTML XHTML The HyperText Markup Language The language used to design web pages The eXtensible HyperText Markup Language Intended to enhance HTML, not replace it World Wide Consortium (W3C) organisation is responsible for developing web standards Content of Web Pages A web site may contain a combination of 13 standard elements: Text Lists Hyperlinks Colour Graphics Images Image Maps Sound Video Tables Layers Frames Forms Content 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., banking web sites, weather reports… Authoring of Web Pages After a web page is designed one needs to use HTML/XHTML code to author a web page XHTML Syntax XHTML uses tags that are enclosed in brackets (<,>) XHTML content is enclosed between the tags Tags and content form an XHTML Generic form: <starttag>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 Syntax XHTML rules Tags must be closed Empty tags must be closed Use lower case tags White space matters All attributes values must be quoted Tags must not overlap (i.e., during nesting) Comments can be used XHTML uses escaped characters Do not use deprecated or obsolete tags Browsers ignore mis-spelled tags HTML Document Structure <html> <head> <title>HTML Document Structure</title> <meta name="author" content=“yupeng"> </head> <body> Web page content goes here </body> </html> XHTML Document Structure <?xml version="1.0" encoding="iso-8859-1"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta name="author" content=“yupeng”/> <title>XHTML Document Structure</title> </head> <body> Web page content goes here </body> </html> Document Tags The tags that make up the framework of a typical HTML document include the following: Document type tag – DOCTYPE <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> Top-level tag, generally <html> Tag indicates the beginning and end of an XHTML document Document Tags - Header Header section, delimited by <head> tags Provides extra information about the document Serves as a container such as styles and global scripts 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 Document Tags - Body Body section, delimited by <body> tags Section where visible content appears Content is a series of block tags containing inline content XHTML Tags <!DOCTYPE ….> <html> <head> ….. </head> <body> ….. </body> </html> How can I write my first web page? 1. 2. 3. 4. Open a text editor e.g., Notepad Put in code from the HTML Document Structure Slide Save it as Example1.html In web browser (IE/Firefox/Chrome), Select File -> Open Select Example1.html Select Open Meta 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, scheme Meta Tags <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 the keywords to agents requesting them Some search engines use these keywords to categorise the document for searching Amazon’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" /> Authoring Tools Tools need to develop a web site: Types of editors Editor Graphics program Digital cameras Scanners Audio & video software 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 Text Formatting Paragraphs Lines Headings Horizontal Rules Block divisions Paragraphs Main textual blocks, delimited by <p> tags <p>This a paragraph of text in an XHTML document</p> Line space This a paragraph of text in an XHTML document Lines Used when you need to break a line prematurely (before the paragraph) The line break tag is <br/> Lines - Example <p>This a paragraph of text in an XHTML document</p> <p>This a 2nd paragraph of text in an XHTML document</p> This a paragraph of text in an XHTML document This a 2nd paragraph of text in an XHTML document <p>This a paragraph of text in an XHTML document</p> <br/> <p>This a 2nd paragraph of text in an XHTML document</p> This a paragraph of text in an XHTML document This a 2nd paragraph of text in an XHTML document Headings 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 1 Heading 2 Heading 3 Heading 4 Heading 5 Heading 6 Horizontal Rules Horizontal rules appear as lines across the user agent screen - <hr/> Used to separate information visually A line should be drawn under this text <hr/> A line should be drawn under this text Block Divisions 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 quote should 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 Formatting Text Headings <h1> largest . . <h6> smallest Paragraphs <p> Word/Characters <b> bold <i> italic <br/> line break <div> acts like a line break <hr/> line in a web page, Special Characters These are required because some characters are reserved for XHTML use such as ‘<‘,’>’, etc. Special characters are represented by a character entity or a numeric code The character entity begins with & and ends with; © ->© The numeric code begins with &# and ends with ; © -> © 3 distinct character sets are: ISO 8859-1 (Latin – 1) Symbols, mathematical symbols, and Greek letters Markup-significant and internationalisation characters Hyperlinks Hyperlinks link web pages to each other Hyperlinks can be used as: A link is a connection from one source to another Hyperlinks create hypertext and is the driving force of the web Links (inter-document links) Anchors (intra-document links) Links start at the source (visible part) and points to the destination (invisible part) <a invisible part> visible part</a> Text or image File / web page/ program/ image/ video or Audio file….etc. Hyperlinks The important attributes of the <a> tag: href title name charset type rel rev accesskey shape coords Hyperlinks 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 Example: <a href=http://www.dit.ie> This is the DIT web site</a> Hyperlinks Anchors are <a> tag to link different sections of the same web page 2 uses of anchors are for table of contents and eliminating scrolling Creation of anchor requires 2 <a> tags <a name=“sale”> and <a href=“#sale”> Hyperlinks - anchors <a name="Contents">Table of Contents</a> <a href="#Section1"> Section 1</a> <a name="Section1"> Section 1</a> <a href="#Contents"> Return to Table of Contents</a> Lists XHTML supports 3 types of lists: Ordered – <ol> Unordered – <ul> Definition – <dl> Lists may be nested to obtain multiple hierarchy levels 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> <li>Apples</li> <li>Bananas</li> <li>Coconuts</li> </ol> 1. Apples 2. Bananas 3. Coconuts Ordered List - <ol> How can the numbering style be changed?? <ol style=“list-style-type: lower-alpha”> <li>Apples</li> <li>Bananas</li> <li>Coconuts</li> </ol> Some other style options: decimal lower-roman upper-roman upper-alpha a. Apples b. Bananas c. Coconuts Unordered List - <ul> Lists whose elements do not have to appear in a certain order <ul> <li>Apples</li> <li>Bananas</li> <li>Coconuts</li> </ul> • • • Apples Bananas Coconuts Unordered List - <ul> How can the list item marker be changed?? <ul style=“list-style-type: square”> <li>Apples</li> <li>Bananas</li> <li>Coconuts</li> </ul> Some other style options: disc circle none Apples Bananas Coconuts Definition List - <dl> More complex than the other 2 lists due to their having 2 elements per list item <dl> <dt>Internet Explorer</dt> <dd>Developed by Microsoft</dd> <dt>Netscape</dt> <dd>Developed by Netscape</dd> </dl> Internet Explorer Developed by Microsoft Netscape Developed by Netscape Nesting Lists Lists can be nested of the same or different types <ul> <li>Send us a letter, including:</li> <ol> <li>Your full name</li> <li>Your order number</li> <li>Your contact information</li> </ol> <li> Use the web form to send an email </li> </ul> • • Send us a letter, including: 1. Your full name 2. Your order number 3. You contact information Use the web form to send an email Colours 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 are specified using hexadecimal codes Black -> #000000 Red -> #FF0000 Blue -> #0000FF Colours can be set globally or locally Audio & Video XHTML allows any author 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 is used to incorporate audio and video files in a web page Attributes used are src, width and height, volume, autostart, loop and hidden Audio & Video <embed src="music.mp3" width="145" height="60" volume="70"> </embed> Conclusion Three views of Web pages: URL, browser display, and document Web sites and Web pages Text formatting: text, lists, colors, hyperlinks, audio, video HTML and XHTML Text and HTML editors XHTML document structure Content of Web pages Special characters 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