JavaScript Examples Bible - UserWorks Technologies

The Document
and Body
Objects
(Chapter 18)
To include coverage of the document object and BODY element
object in the same chapter is logical, provided you
don’t fall into a conceptual trap that has been set during the
evolution of document object models. The document object
has been with us since the beginning. Even though it is an
abstract object (that is to say, the object exists simply by virtue
of a page loading into the browser, rather than associated with
any HTML tag), a number of its properties reflect attributes
that are defined in a page’s tag. For instance, the properties
for link colors and background images, whose behaviors
are set in BODY element attributes, have been exposed via the
document object since the earliest days.
In more modern object models (IE4+ and W3C DOM), the
BODY element is its own object. The document object
strengthens its role as a “super-container” of all the HTML element
objects in the page. Thus, the BODY element object is a
child element of the root document object (see Chapter 14 of
the JavaScript Bible for more details). But now that the BODY
element object can expose its own attributes as properties,
the document object no longer needs to play that role, except
for the sake of backward compatibility with scripts written for
older browsers. Instead, the document object assumes an
even greater role, especially in the W3C DOM, by providing
critical properties and methods of a global nature for the
entire document.
4
C H A P T E R
✦ ✦ ✦ ✦
In This Chapter
Accessing arrays of
objects contained by
the document object
Writing new
document content to
a window or frame
Managing BODY
element scrolling in IE
✦ ✦ ✦ ✦