JavaScript Examples Bible - UserWorks Technologies

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JavaScript Examples Bible: The Essential Companion to JavaScript Bible
Note
Figure 8-1: Clicking on button choices reveals additional relevant choices
Notice how the toggle() function was written as a generalizable function. This
function can accept a reference to any checkbox object and any related span. If five
more groups like this were added to the table, no additional functions would be
needed.
In the swap() function, an application of a nested if...else shortcut construction
is used to convert the Boolean values of the checked property to the strings
needed for the display style property. The nesting is used to allow a single statement
to take care of two conditions: the group of buttons to be controlled and the
checked property of the button invoking the function. This function is not generalizable,
because it contains explicit references to objects in the document. The
swap() function can be made generalizable, but due to the special relationships
between pairs of span elements (meaning one has to be hidden while the other displayed
in its place), the function would require more parameters to fill in the blanks
where explicit references are needed.
A rendering bug in NN6 causes the form controls in the lower right frame to lose
their settings when the elements have their display style property set to none.
The problem is related to the inclusion of P or similar block elements inside a
table cell that contains controls. Therefore, if you uncheck and recheck the
Communications checkbox in the example page, the previously displayed subgroup
shows up even though no radio buttons are selected. You can script around
this bug by preserving radio button settings in a global variable as you hide the
group, and restoring the settings when you show the group again.
document.formObject.checkboxObject.onClick