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The Internet Day 8, 9/22 Review HFHTML ch 1 - 7
CIS 228 The Internet Day 8, 9/22 Review HFHTML ch 1 - 7
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Alphabet Soup HTML (delineates document structure)
HyperText Markup Language CSS (specifies document presentation) Cascading Style Sheets XHTML (HTML as an XML sub-language) eXtensible HyperText Markup Language XML eXtensible Markup Language
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An HTML Document <html> <head>
<title>A minimal web page</title> </head> <body> <h1>Hello world!</h1> </body> </html>
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HTML Vocabulary Tag – markup (enclosed in angle brackets)
Opening tags: <html>, <div id=”end”>, <h1>,<p>, <q>, <em> Closing tags: </html>, </div>, </h1>, </p>, </q>, </em> Empty tags: <br>, <hr>, <img src=”photo.jpg” alt=”my pic”> Element – a component of a document An empty tag, or Opening tag, matching closing tag, everything in between Attribute – a name value pair in an opening or empty tag id=”end”, src=”photo.jpg”, alt=”my pic”, class=”address”> Character Entity – special characters & (“&”), < (“<”), > (“>”), © (“©”)
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HTML Character Entities
< < < less than > > > greater than & & & ampersand “ " " double quote ' ' ' apostrophe non-breaking space Required in content, meaningless in markup (tags) More:
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HTML Elements Opening tag, content, closing tag (or empty tag)
Elements Nest (form a document tree) The <html> element is the root Each element is fully contained in a unique parent Two kinds: Block elements (large sections of a document) Inline elements (mostly text) Raw text (e.g. “a mule”) Multiple whitespace chars (“ “, “\t”, “\n”) collapse to a singe space Short sections of text (e.g “a <em>very stupid</em> mule”)
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Kinds of HTML Elements Block elements Inline elements:
Containing other block elements: <html>, <head>, <body>, <div>, <blockquote> Containing only inline elements: Titles (in <head> element): <title> ?? Headings: <h1>, <h2>, <h3>, <h4>, <h5>, <h6> Paragraphs: <p> Inline elements: <q> quote <em> emphasis (often italic) <strong> emphasis (often bold)
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Some HTML Elements <html> contains <head> and <body> elements <head> contains information about the page <body> contains the page content <h1> contains inline elements that make up a heading <h2> a slightly less dramatic heading <p> contains inline elements that make up a paragraph <q> an inline quotation <em> inline element indicating emphasis <strong> inline element also indicating emphasis <img> an empty element indicating a picture <br> an empty element indicating a line break
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Style Element <style> element helps determine page presentation
Parent is the <head> element Attribute type=“text/css” Content consists of CSS declarations <style type=“text/css”> body { background-color: #db8; Margin: 10%; font-family: sans-serif; } </style> Style information will be stored in separate files
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Web Vocabulary Web page – the unit of hypertext content stored on a server and displayed by a browser Server – a repository for web pages, which are delivered to browsers upon request Browser – obtains web pages specified (explicitly or implicitly via a hyperlink) by a user and displays their contents to the user Hyperlink – clickable html element that indicates a transition to a web page specified by an attribute in the opening tag of the element Hypertext – text containing one or more hyperlinks
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Hypertext <a> element specifies a hyperlink
Content (the link label) is clickable CSS specifies how this content is displayed Usually underlined and in a distinctive color href attribute specifies a new web page As a path to a file on the same computer, or As URL (Uniform Resource Locator) title attribute is a textual description of the page Suggestion: title attribute should match page's title element id attribute provides a destination for hyperlinks target attributes specifies different window (or tab)
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URL's Uniform Resource Locator
protocol://domain:port/path#fragment Protocol – a scheme for exchanging information http (hypertext transfer protocol), ftp, etc. Domain – identifies a server Port – optional number for the protocol to use Path – specifies a file on the server Fragment – specifies a location within the file
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Domain Names Top level: com, org, net, edu, mil, …
ICANN decides these Second level: google.com, cuny.edu, … You can acquire these Provided by Domain Name Registrars ($10/year) Go Daddy, eNom, Tucows, Melbourne IT, Key-Systems Deeper level: lehman.cuny.edu Administered by the second level name owner Typically, the first name identifies a machine media.lehman.cuny.edu
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Paths Path – sequence of names separated by “/”s
The final name in a path specifies a file Fragments “#loc” specify locations within a file Other names specify directories (folders) To go down, specify the name of the child directory To go up, use “..” Examples: trucks.html Second Kings/22/20.html ../../../second/cousin/once/removed.html
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Hyperlink Examples <a href=“todo.html” title=“todo”>todo</a> <a href=“ Directions </a> <a href=“../fire/trucks.html” title=“trucks”> My firetruck page <a href=“ title=“office hour”>My office hour <a href=“../library/books#catch22” title=“citation”> Catch 22
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The Image Element An inline element that identifies an image to display Tag: <img> (an empty element, no closing tag) src attribute, where to find the image Relative path to a local file, or Uniform Resource Locator alt attribute, textual indication of what the image is width attribute, provides browser with size info height attribute, provides browser with size info Use width (and height) to inform the browser Not to resize a large image (why?)
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Common Image Formats jpg gif (depricated ??) png psd
Variable, lossy data compression Good for photos (lots of colors) gif (depricated ??) Good for logos (small number or colors) Transparency png Newer format with transparency (replacing gif ?) psd Proprietary, Adobe Photoshop format
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“Quirks” Mode Today, all browsers support standards
Compliant pages are displayed similarly There are multiple standards HTML 4, HTML 4.01, XHTML 1.0, XHTML 1.1, … Browsers need to know which standard a page adheres to Browsers still need to support old web pages Each browser does this differently (and slowly) To avoid “quirks” mode DOCTYPE announces the standard your page uses Make sure your page obeys that standard.
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DOCTYPE On the top line of your html file HTML 4.01 (transitional)
Only a handfull to choose from Spelling (including capitalization) must be identical HTML 4.01 (transitional) <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" " HTML 4.01 (strict) <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" " XHTML 1.0 (strict) <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Strict//EN" "
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HTML 4.01 Compliance Issues
Images need an alt attribute Specify a character encoding <meta http-equiv=”Content-Type” content=“text/html; charset=utf-8”> Don't leave off end (or start) tag html element required Containing head and body elements (and nothing else) title element required in head element Only block elements nest directly in body or blockquote Block elements cannot be in p or inline elements a elements cannot contain other a elements List elements (ol and ul) only contain list items (li)
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XHTML 1.0 Strict Well-formed XML (empty elements end “ />”)
XML declaration (optional) <?xml version="1.0" encoding="UTF-8" ?> Document Type Declaration <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" " > Root element <html xmlns=" xml:lang="en" lang="en" >
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Well-formed XML Document needs to contain at least 1 element
Unique root element contains whole document Tags must nest properly Empty tags end “/>” Tag names are case sensitive Attribute values must be quoted Characters “<”, “>”, “&”, “'”, and '”' Cannot appear in content Use character entities (< >, …) instead
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Study Suggestions Read the text (if you haven't already)
Repeat any labs you aren't confident about Take the practice exam (if you haven't already) Look over the answer key for the practice exam Review the “bullet points” at the end of each chapter Review these slides Ignore: internet history, FTP, XML, image processing Look over the “there are no Dumb Questions” sections of the text
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