ITEC 325 2012spring ibarland

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xhtml-and-html
xhtml and html

• Review: write a loop that sums array(31,29,31,30)
• Btw, happy Imbolc
• HTML review:
  HTML is a (text representation of) a tree. The tree [as it exists in memory of the browser's program] is also the called the Document Object Model, or "DOM".
• Each tag has three parts:
  tag-name
  attributes (name/value pairs)
  children
  
• A more precise (but not-quite-complete) definition: An HTML-node is EITHER:
  • a tag,
  • an entity
  • a string (well, a pc-string)
  WHERE:
  • a tag is: a tag-name (a lower-case word), and 0 or more attributes (an name/value pair), and a body (which is a list-of-HTML-nodes):
    <name attrName="attrValue"…>body</name>
  • an entity is &someWord; where someWord is just a pc-string without whitespace.
    
  • A pc-string (parsed character string) is any string without¹the five characters    <    >    &    "    '
• Btw, what's the difference between the meaning of em and i tags? (And, cite.) Cf. a web-bot trolling for data, vs a voice-interface to the web.
• There are three attributes with special meaning in HTML:
  
  • id - specify a unique node. The same value can't be used for the id attribute of two different tags.
  • name - specify a set of nodes. All the related nodes can use the same value for their name attribute, to indicate their relation.
  • class - used by css. Don't be too specific here; try to use a class that corresponds to some semantics: e.g. “menuItem”, not “boldItalic”.

• There are also entities. &mdash;, &hellip;. An entity represents an atomic² piece of information: often a single glyph/fancy-charcater, but in theory you could use an entity for a logo or a motto.

  There are five entities that are common to any xml (not just html/xhtml):

  • &amp; (&)
  • &lt; (<)
  • &gt; (>)
  • &apos; (')
  • &quot; (")

• xhtml :
  • quote all attribute-values, even if it looks numeric;
  • well-formed (duh): each open-tag must be eventually followed by a corresponding close-tag, and if a tag's body contains another open-tag it must also contain the corresponding close-tag.
  • tag names are case-sensitive (with a preference for lower-case and camelCase).
  Note self-closing tags, and when they can be used: Only if the tag can't contain data. So “<hr />” is shorthand for “<hr></hr>”, but “<script src="foo.js" />” is not allowed, because the script tag can also sometimes contain content. (There is no good reason for this.)
• 2 common “dummy” tags: span, div. These are used when you want to group several in-line elements (or, block-elements resp.)

  For example, you might want to give a “name” attribute to every mention of an indian-tribe in your document. But the tribe-names are just regular text, so there isn't a natural a or cite or tag to use. Instead we can put them in a span tag:

         The <span name="clan">Catawba tribe</span> and
         the <span name="clan">Powhatan Confederacy</span> each
         roamed the part of the earth now known as “Virginia”.

  This has no effect on mark-up. span and div are commonly used to apply a class attribute to a section of a page (and class attributes are in turn often used to implement a 'virtual tag' invented by the author specific to that document)… See also the XSLT processing, for a more heavyweight approach to doing this.

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©2011, Ian Barland, Radford University Last modified 2012.Feb.06 (Mon)

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