JavaScript Examples Bible - UserWorks Technologies

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JavaScript Examples Bible: The Essential Companion to JavaScript Bible
elementObject.onKeyDown
onKeyDown, onKeyPress, and onKeyUp events. If you hold down one or more modifier
keys while performing the key press, the modifier key name is highlighted for
each of the three events. Note that when run in NN6, the keyCode value is not the
character code (which doesn’t show up in this example for NN6). Also, you may need
to click the NN6 page for the document object to recognize the keyboard events.
The best way to watch what goes on during keyboard events is to press and hold
a key to see the key codes for the onKeyDown and onKeyPress events (see Figure
1-5). Then release the key to see the code for the onKeyUp event. Notice, for
instance, that if you press the A key without any modifier key, the onKeyDown event
key code is 65 (A) but the onKeyPress key code in IE (and the charCode property
in NN6 if it were displayed here) is 97 (a). If you then repeat the exercise but hold
the Shift key down, all three events generate the 65 (A) key code (and the Shift modifier
labels are highlighted). Releasing the Shift key causes the onKeyUp event to
show the key code for the Shift key.
Figure 1-5: Pressing Ctrl+Alt+J in the keyboard event lab page
In another experiment, press any of the four arrow keys. No key code is passed
for the onKeyPress event because those keys don’t generate those events. They
do, however, generate onKeyDown and onKeyUp events.
Listing 15-41: Keyboard Event Handler Laboratory
Keyboard Event Handler Lab
TD {text-align:center}
function init() {
document.onkeydown = showKeyDown
document.onkeyup = showKeyUp