JavaScript Examples Bible - UserWorks Technologies

370
SELECT.multiple
JavaScript Examples Bible: The Essential Companion to JavaScript Bible
Examples Highlights
✦ To harvest the values of all selected items in a multiple list, your script needs
to cycle through the SELECT element’s options array and inspect the
selected property of each, as shown in Listing 26-4.
✦ Scripts can also retrieve the text of the selected item, instead of the hidden
value. Compare two similar applications that work with the text (Listing 26-5)
and value (Listing 26-6) properties.
✦ Listings 26-5 and 26-6 show the backward-compatible, long reference to
retrieve a chosen option’s details. The modern alternative accompanies the
example for the SELECT.value property.
✦ See Listing 26-8 for another example of triggering a script via the onChange
event handler of a SELECT object.
✦ Implementations of the OPTGROUP element object may need improvement
before Listing 26-9 behaves as it should to modify hierarchical labels within a
SELECT list.
SELECT Element Object
Properties
length
NN2 NN3 NN4 NN6 IE3/J1 IE3/J2 IE4 IE5 IE5.5
Compatibility ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
Example
See Listing 26-1 in Chapter 26 of the JavaScript Bible for an illustration of the way
you use the length property to help determine how often to cycle through the
repeat loop in search of selected items. Because the loop counter, i, must start at 0,
the counting continues until the loop counter is one less than the actual length
value (which starts its count with 1).
multiple
NN2 NN3 NN4 NN6 IE3/J1 IE3/J2 IE4 IE5 IE5.5
Compatibility ✓ ✓ ✓ ✓
Example
The following statement toggles between single and multiple selections on a
SELECT element object whose SIZE attribute is set to a value greater than 1: