JavaScript Examples Bible - UserWorks Technologies

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JavaScript Examples Bible: The Essential Companion to JavaScript Bible
✦ Follow the steps for the disabled property to see how form controls can be
disabled in IE4+ and NN6. IE5.5 lets you disable any element on the page, as
you can witness in real time when you follow the example steps.
✦ Long-time IE scripters know the powers of the innerHTML and innerText
properties. Listing 15-11 solidifies by example the precise differences between
the two related properties. Only one of these properties, innerHTML, is
implemented in NN6.
✦ Grasping the details of properties that govern element positions and dimensions
is not easy, as noted in the JavaScript Bible text. But you can work through
the examples of the client-, offset-, and scroll-related properties for IE4+ and the
offset-related properties in NN6 to help you visualize what these properties control.
If you are scripting cross-browser applications, be sure to work through the
offset-related properties in both browsers to compare the results.
✦ Compare the IE5+ attachEvent() method and NN6 addEventListener()
method for modern ways to assign event handlers to element objects.
Although the method names are different, the two work identically.
✦ Observe how the getAttribute() method returns an object’s property value
when the property name is a string and the name is the same as an assigned
element attribute name. The getAttribute() method is the prescribed way
to retrieve property values according to the W3C DOM.
✦ You can see how the getElementsByTagName() method returns an array of
nested elements with a particular tag. This is a great way, for example, to get a
one-dimensional array of all cells within a table.
✦ Spend time comparing how the various insert- and replace-related methods
operate from different points of view. In the IE world, most operate on the current
element; in the W3C DOM world, the methods operate on child nodes of
the current element.
✦ For IE5+/Windows, check out the way dynamic properties are managed
through the getExpression(), setExpression(), and recalc() methods.
Listing 15-32 demonstrates a neat graphical clock that employs these methods.
✦ IE5+/Windows provides a number of event handlers, such as onBeforeCopy,
onBeforePaste, onCopy, onCut, and onPaste that let scripts manage the
specific information preserved in the clipboard. These event handlers can
also be used with the onContextMenu event handler to facilitate custom
context menus.
✦ Another set of IE5+/Windows event handlers provides excellent control over
user dragging and dropping of elements on a page. Listing 15-37 is particularly
interesting in this regard.
✦ Listing 15-41 shows a cross-browser laboratory for understanding the three
keyboard events and how to get key and character information from the event.
You see event-handling that works with IE4+, NN4, and NN6 event models.
✦ Numerous mouse-related events belong to all HTML elements. Listings 15-42
and 15-43 demonstrate simplified image swapping and element dragging.