[Accessibility-handlers] updated minutes from 21 april 2008 handlers call
Gregory J. Rosmaita
unagi69 at concentric.net
Wed Apr 23 12:36:45 PDT 2008
aloha!
thanks to pete for his additions to the record of the 21 april 2008 handlers
call:
https://www.linux-foundation.org/en/Accessibility/Handlers/Meetings/Minutes20080421.html
i, too, just modified the minutes, adding annotations, links,
formatting, and (most important/germane), extracts from the Element
Traversal working draft about which i informed the group (and to which i've
placed a link as a reference in these and past minutes) during the call...
if anyone else has anything to add, correct or modify, please either do
so yourself (you need to have a linux foundation wiki account to edit
the minutes) or reply-to this post and i'll effect whatever changes are
necessary...
i'm going to include the important bits about the Element Transversal
draft after my signature, but if you use the hypertext version of the
minutes, you will be able to follow the links embedded in the quotes,
gregory.
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Element Traversal Specification:
http://www.w3.org/TR/2008/WD-ElementTraversal-20080303/
Abstract
This specification defines the ElementTraversal interface,
which allows script navigation of the elements of a DOM tree,
excluding all other nodes in the DOM, such as text nodes. It
also provides an attribute to expose the number of child
elements of an element. It is intended to provide a more
convenient alternative to existing DOM navigation interfaces,
with a low implementation footprint.
1. Introduction
This section is informative.
The DOM Level 1 Node interface defines 11 node types, but most
commonly authors wish to operate solely on nodeType 1, the
Element node. Other node types include the Document element and
Text nodes, which include whitespace and line breaks. DOM 1 node
traversal includes all of these node types, which is often a
source of confusion for authors and which requires an extra step
for authors to confirm that the expected Element node interfaces
are available. This introduces an additional performance
constraint.
ElementTraversal is an interface which allows the author to
restrict navigation to Element nodes. It permits navigation from
an element to its first element child, its last element child,
and to its next or previous element siblings. Because the
implementation exposes only the element nodes, the memory and
computational footprint of the DOM representation can be
optimized for constrained devices.
The DOM Level 1 Node interface also defines the childNodes
attribute, which is a live list of all child nodes of the node;
the childNodes list has a length attribute to expose the total
number of child nodes of all nodeTypes, useful for preprocessing
operations and calculations before, or instead of, looping
through the child nodes. The ElementTraversal interface has a
similar attribute, childElementCount, that reports only the
number of Element nodes, which is often what is desired for such
operations.
2. ElementTraversal interface
This section is normative.
The ElementTraversal interface is a set of attributes which allow
an author to easily navigate between elements in a document. In
conforming implementations of Element Traversal, all objects that
implement Element must also implement Element Traversal. Four of
the attributes, firstElementChild, lastElementChild,
previousElementSibling, and nextElementSibling, each provide a
live reference to another element with the defined relationship to
the current element, if the related element exists. The fifth
attribute, childElementCount, exposes the number of child elements
of an element, for preprocessing before navigation. A conforming
User Agent must implement all five attributes. A User Agent may
implement similar interfaces in other specifications, but such
implementation is not required for conformance to this
specification, if the User Agent is designed for a minimal code
footprint.
This interface must be implemented on all elements, regardless of
their namespace. For the purpose of Element Traversal, an entity
reference node which represents an element must be treated as an
element node. Navigation must be irrespective of namespace, e.g.
if an element in the HTML namespace is followed by element in the
SVG namespace, the nextElementSibling attribute on the HTML
element will return the SVG element.
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A conclusion is simply the place where someone got tired of thinking.
-- Arthur Bloc
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Gregory J. Rosmaita - oedipus at hicom.net AND gregory at ubats.org
Camera Obscura: http://www.hicom.net/~oedipus/
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