JavaScript Examples Bible - UserWorks Technologies

The NN4
Layer Object
(Chapter 31)
Chapter 31 of the JavaScript Bible is devoted to positioned
objects in all object models. Only Navigator 4 has its
own set of dedicated positionable objects: the LAYER and
ILAYER element objects. In the IE4+ and W3C DOMs, virtually
any renderable element is positionable, although it is common
practice to restrict such activity to SPAN and DIV elements.
Because properties of the SPAN, DIV, and other HTML element
objects are covered in detail in other chapters, Chapter 31
provides the details of the NN4 layer object.
Examples shown here support NN4 layer object details, but
the rest of the discussion and code listings in JavaScript Bible
Chapter 31 go to great lengths to recreate the same behaviors
in both the IE4+ and W3C (NN6) object models. This will help
those scripters who developed extensively for NN4’s Dynamic
HTML make the transition to NN6 and its support for Dynamic
HTML (which is not much different from that in the IE4+ object
model). Obviously, all examples shown below require NN4.
Examples Highlights
✦ Clipping of layer rectangles is not an easy concept to
grasp at first (in any object model). Listing 31-2 provides
a workbench to explore the various properties associated
with the clipping rectangle. Listing 31-5 demonstrates
the relationship between moving a layer and
adjusting its clipping rectangle.
✦ Listing 31-6 is an extensive demonstration of a variety of
layer coordinate system properties.
✦ Most layer object properties are handled in later object
models through style sheet property manipulation.
Listing 31-8 shows the NN4 layer way of handling a
layer’s visibility, while Listing 31-9 demonstrates adjusting
the stacking order of layers.
15
C H A P T E R
✦ ✦ ✦ ✦
In This Chapter
Using NN4-specific
syntax for positioned
elements
How to move, hide,
and show positioned
content in NN4
Setting the clipping
rectangle of a layer
in NN4
✦ ✦ ✦ ✦