JavaScript Examples Bible - UserWorks Technologies

Note
Chapter 5 ✦ Body Text Objects (Chapter 19)
three FONT object properties, and their NAME attributes are strategically assigned
the names of the properties (as you see in a moment). VALUE attributes for OPTION
elements contain strings that are to be assigned to the various properties. Each
SELECT element invokes the same setFontAttr() function, passing a reference to
itself so that the function can inspect details of the element.
The first task of the setFontAttr() function is to make sure that only browsers
capable of treating the FONT element as an object get to the meat of the function.
The test for the existence of document.all and the myFONT element blocks all
older browsers from changing the font characteristics. As the page loads, the
document.all property is set for NN6 by using a variation of the normalization
technique described in Chapter 14 of the JavaScript Bible.
For suitably equipped browsers, the function next extracts the string from the
value property of the SELECT object that was passed to the function. If a selection
is made (meaning other than the first, empty one), then the single nested statement
uses the setAttribute() method to assign the value to the attribute whose name
matches the name of the SELECT element.
An odd bug in IE5/Mac doesn’t let the rendered color change when changing the
color property. But the setting is valid, as proven by selecting any of the other
two property choices.
Listing 19-1: Controlling FONT Object Properties
FONT Object Properties
// document.all normalization trick for NN6
if (navigator.appName == “Netscape” && parseInt(navigator.appVersion) >= 5) {
document.all = document.getElementsByTagName(“*”)
}
// one function does all!
function setFontAttr(select) {
if (document.all && document.all.myFONT) {
var choice = select.options[select.selectedIndex].value
if (choice) {
document.all.myFONT.setAttribute(select.name, choice)
}
}
}
Font Object Properties
Continued
267
FONT.color