EECS1012. Net-centric Introduction to Computing. Lecture 2: HTML

Size: px

Start display at page:

Download "EECS1012. Net-centric Introduction to Computing. Lecture 2: HTML"

Imogene Ross
6 years ago
Views:

1 EECS1012 Net-centric Introduction to Computing Lecture 2: Acknowledgements Contents are adapted from web lectures for Web Programming Step by Step, by M. Stepp, J. Miller, and V. Kirst Slides have been ported to PPT by Dr. Xenia Mountrouidou These slides have been edited for EECS1012, York University The contents of these slides may be modified and redistributed, please give appropriate credit. M.S. Brown, EECS York University 1 (Creative Commons) Michael S. Brown, 2017

2 2 Basic

3 Hypertext Markup Language () 3 Describes the content and structure of information on a web page Not the same as the presentation (appearance on the screen) Surrounds text content with opening and closing tags Each tag's name is called an element syntax: <element> content </element> example: <p>this is a paragraph</p> EECS 1012 CS380

4 5 4 The latest version of, standardize in 2017 Initial recommendation started in 2008 Gives you an idea of how long it takes to standardize a markup language Our examples will focus on 5 IE8 in Windows may not always support it Get yourself a better browser!

5 Structure of page 5 <!DOCTYPE html> <html> <head> information about the page </head> <body> page contents </body> </html> is saved with extension.html Basic structure: tags that enclose content, i.e., elements Header describes the page Body contains the page s contents

6 Structure of page 6 <!DOCTYPE html> <html>.. </html> All pages should start with a <!DOCTYPE html>. This is not part of the standard.. However, this is used by the browser to know what type of document it is loading (e.g. maybe an older 2.0, etc see here) <!DOCTYPE html> is used for 5, and is required to be considered a valid html5 document. This will be important when we validate our files later.

7 Page title <title> 7 <head> <title> Chapter 2: </title> </head> Placed within the head of the page Displayed in web browser s title mark and when bookmarking the page

8 Specifying the document encoding 8 <head> <meta charset= UTF-8 > </head> Strict 5 requires that the charset used to encode the document be specified. UTF is a standard 8-bit encoding used by virtually all servers these days. The details are bit overly complex, so for now just believe me that you need to have the above tag in your <head> </head> section.

9 Paragraph <p> 9 <body> <p>whatever you do will be insignificant, but it is very important that you do it.</p> </body> Whatever you do will be insignificant, but it is very important that you do it. output Placed within the body of the page Note that whitespace and new lines * are ignored. *What is a new line? When you hit enter on your keyboard, it generates a new line character that moves to the next line in the document.

10 Headings <h1>, <h2>, <h6> 10 <h1> Harry Potter </h1> <h2> Books </h2> <h3> Harry Potter and the Philosopher s Stone </h3> Harry Potter Books Harry Potter and the Philosopher s Stone More examples output

11 Horizontal rule <hr> 11 <p> First paragraph </p> <hr> <p> Second Paragraph </p> First Paragraph Second Paragraph Generates a line between paragraphs. Note that this does not require a closing </hr> output This type of element is called an empty element (or a void element)

12 Block and Inline elements 12 Block elements contain an entire large region of content examples: paragraphs, lists, table cells the browser places a margin of whitespace between block elements for separation

13 Block and Inline elements (cont.) 13 Inline elements affect a small amount of content Examples: bold text, code fragments, images the browser allows many inline elements to appear on the same line must be nested inside a block element

14 More info on block and inline 14 See more information here: When you use CSS (next lecture) you will often need to remember if an element is a block or an inline element - it will behave differently.

15 More about tags 15 Some tags can contain additional information called attributes syntax: <element attribute="value" attribute="value"> content </element> example: <a href="page2.html">next page</a>

16 Even more about tags 16 Some tags don't contain content between the tags (they may specify content but not between the tags); these tags can be opened and closed in one tag syntax: <element attribute="value" attribute="value"> example: <hr> example: <img src= Harry.jpg" alt="pic of Harry Potter">

17 Links <a> 17 <p> Search <a href=" now! </p> Search Google now! output The href attribute specifies the destination URL Links or anchors are inline elements, so they must be placed inside a block element such as a p or h1

18 More about links/anchors 18 <p><a href= deathlyhallows-book.html">harry Potter and the Deathly Hallows Book</a></p> <p><a href=" title="search">wikipedia</a></p> Harry Potter and the Deathly Hallows Wikipedia output Types of URLs that can appear in anchors: Absolute: to another web site Relative: to another page on this web site

19 Target _blank attribute 19 <p><a target= _blank href=" title="search">wikipedia</a></p> Wikipedia output Target attribute Setting the target attribute to _blank (with a leading underscore character) will force the link to open in a new tab or page.

20 Nesting tags 20 Bad.. don t do this <p> <a href=" deathlyhallows-book.html"> Harry Potter and the Deathly Hallows Book </p> <p> <p> tag was closed before the <a> tag. This text also links to Harry Potter Book </a> </p> Tags must be correctly nested: a closing tag must match the most recently opened tag The browser may render it correctly anyway, but it is invalid 5 * I ll use a Deaner icon to denote a bad example.

21 Image element <img> 21 <img src="images/tobby.jpg" alt= Tobby from Harry Potter"> The src attribute specifies source of the image URL 5 also requires an alt attribute describing the image.. this gives a text description when for some reason the user cannot view it (slow connection, text only browser)

Images as link content 22 <a href="http://www.mugglenet.com/ > <img src="images/dumbledore.

22 Images as link content 22 <a href=" > <img src="images/dumbledore.jpg" alt= Dumbledore from Harry Potter" title="alas! Ear wax!"> </a> If placed inside an a anchor, the image will become a link The title attribute specifies an optional tooltip

23 Line break <br> 23 <p>teddy said it was a hat, <br> So I put it on.</p> <p>now Daddy's sayin', <br> Where the heck's the toilet plunger gone?</p> Teddy said it was a hat, So I put it on. Now Daddy's sayin', Where the heck's the toilet plunger gone? output br should not be used to separate paragraphs or used multiple times in a row to create spacing

24 Comments  a lot of fun!</p> EECS courses are a lot of fun! output Comments are useful for disabling sections of a page Useful for adding in information about the page Comments cannot be nested and cannot contain a --

25 Phrase elements <em>, <strong> 25 <p> is <em>really</em>, <strong>really</strong> fun! </p> is really REALLY fun! output em: emphasized text (usually in italic) strong: strongly emphasized text (usually in bold) The tags must be properly nested for a valid page

26 Unordered list: <ul>, <li> 26 <ul> <li>no shoes</li> <li>no shirt</li> <li>no problem!</li> </ul> No shoes No shirt No problem! output ul represents a bulleted list of items (block) li represents a single item within the list (block)

27 Nesting lists 27 <ul> <li>harry <li>harry Potter characters: Potter characters: <ul> <ul> <li>harry Potter</li> <li>harry Potter</li> <li>hermione</li> <li>hermione</li> <li>ron</li> <li>ron</li> </ul> </ul> </li> </li> <li>lotr <li>lotr characters: characters: <ul> <ul> <li>frodo</li> <li>bilbo</li> <li>sam</li> </ul> </li> </ul> </ul> </li> <li>frodo</li> <li>bilbo</li> <li>sam</li>

28 Output from previous slide 28 Harry Potter characters: Harry Potter Hermione Ron LOTR characters: Frodo Bilbo Sam output

29 Ordered list <ol> 29 <p>apple business model:</p> <ol> <li>beat Microsoft</li> <li>beat Google</li> <li>conquer the world!</li> </ol> Apple business model: 1. Beat Microsoft 2. Beat Google 3. Conquer the world output ol represents a numbered list of items we can make lists with letters or Roman numerals using CSS (later)

30 Common error: Not closing a list 30 <ul> <li>no shoes</li> <li>no shirt</li> <li>no problem!</li> <p>paragraph after list...</p> No shoes No shirt No problem! Paragraph after list... output If you leave a list open, subsequent contents will be indented (to correct, you need to insert a </ul>)

31 31 Common Error!: Improper nested list placement <ul> <li>harry Potter characters:</li> <ul> <li>harry Potter</li> <li>hermione</li> <li>ron</li> </ul> </li> <li>lotr characters: <ul> <li>frodo</li> <li>bilbo</li> <li>sam</li> </ul> </ul> closing the outer li too early (or not at all) will render correctly in most browsers, but it is incorrect

32 Definition list <dl>, <dt>, <dd> 32 <dl> <dt>newbie</dt> <dd>one who does not have mad skills</dd> <dt>jaded</dt> <dd>tired, bored, or lacking enthusiasm </dd> <dt>frag</dt> <dd>a kill in a shooting game</dd> </dl> newbie one who does not have mad skills jaded Tired, bored, or lacking enthusiasm frag a kill in a shooting game dl represents a list of definitions of terms dt represents each term, and dd its definition output

33 Tables <table>, <tr>, <td> 33 <table> <tr><td>1,1</td><td>1,2 okay</td></tr> <tr><td>2,1 real wide</td><td>2,2</td></tr> </table> 1,1 1,2 okay 2,1 real wide 2,2 output table defines the overall table, tr each row, and td each cell's data Useful for displaying large row/column data sets NOTE: tables are sometimes used by novices for web page layout, but this is not proper semantic and should be avoided

34 34 Table headers, captions: <th>, <caption> <table> <caption>my important data</caption> <tr><th>column 1</th><th>Column 2</th></tr> <tr><td>1,1</td><td>1,2 okay</td></tr> <tr><td>2,1 real wide</td><td>2,2</td></tr> </table> My important data Column 1 Column 2 1,1 1,2 okay 2,1 real wide 2,2 th cells in a row are considered headers a caption at the start of the table labels its meaning output

35 Quotations <blockquote> 35 <p>as Lincoln said in his famous Gettysburg Address:</p> <blockquote> <p>fourscore and seven years ago, our fathers brought forth on this continent a new nation, conceived in liberty, and dedicated to the proposition that all men are created equal.</p> </blockquote> As Lincoln said in his famous Gettysburg Address: Fourscore and seven years ago, our fathers brought forth on this continent a new nation, conceived in liberty, and dedicated to the proposition that all men are created equal. output a lengthy quotation

36 Inline quotations <q> 36 <p>quoth the Raven, <q>nevermore.</q></p> Quoth the Raven, Nevermore. output a short quotation Why not just write the following? <p>quoth the Raven, "Nevermore."</p> using <q> allows us to apply CSS styles to quotations

37 character entities 37 List of characters entities Question: how would you display the text & on a web page?

38 Using entities 38 <p> <a href=" 8&aq=t"> Search Google for Deaner </a> </p> <p> <a href=" Search Google for Xenia </a> </p> output To display the link text in a web page, its special characters must be encoded as shown above

39 Computer code <code> 39 <p> The <code>ul</code> and <code>ol</code> tags make lists. </p> The ul and ol tags make lists. output code: a short section of computer code

40 Preformatted text <pre> 40 <pre> Bill Gates speaks You will be assimilated Microsoft fans delirious </pre> Bill Gates speaks You will be assimilated Microsoft fans delirious output Displayed with exactly the whitespace / line breaks given in the text Shown in a fixed-width font by default

41 <pre> and <code> together 41 <pre><code> public static void main(string[] args) { System.out.println("Hello, world!"); } </code></pre> public static void main(string[] args) { System.out.println("Hello, world!"); } output When showing a large section of computer code, enclose it in a pre to preserve whitespace and a code to describe the semantics of the content

42 Web standards 42 Why use 5 and web standards? more rigid and structured language more interoperable across different web browsers more likely that our pages will display correctly in the future

W3C 5 Validator 43 https://validator.w3.

43 W3C 5 Validator 43 checks your code to make sure it meets the official strict 5 specifications Very useful for finding bugs in your code

44 Web page metadata <meta> 44 <meta name="description" content= Harry Potter Official Website."> <meta name="keywords" content="harry potter, harry potter and the deathly hallows, deathly hallows, ministry of magic, resurrection stone, clock of invisibility"> <meta charset= UTF-8 > information about your page (for a browser, search engine, etc.) placed in the head of your page meta tags often have both the name and content attributes

45 meta element to describe the page 45 <head> <meta name="author" content="web page's author"> <meta name="revised" content="web page version and/or last modification date"> <meta name="generator" content="the software used to create the page"> </head> many WYSIWYG editors (FrontPage, PageMaker, etc.) place their names in the meta generator tag (why?)

46 meta element to aid search engines 46 <head> <meta name="description" content="how you want search engines to display your page"> <meta name="keywords" content="words to associate with your page (comma separated)"> </head> these are suggestions to search engines about how to index your page the search engine may choose to ignore them (why?)

CSC 443: Web Programming

1 CSC 443: Web Programming Haidar Harmanani Department of Computer Science and Mathematics Lebanese American University Byblos, 1401 2010 Lebanon 2 Basic Haidar Harmanani Department of Computer Science