JavaScript Examples Bible - UserWorks Technologies

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JavaScript Examples Bible: The Essential Companion to JavaScript Bible
Listing 29-18 (continued)
Eventevent.charCodeevent.keyCode
onKeyDown:
onKeyPress:
onKeyUp:
Here are some specific tasks to try with the page to examine key codes (if you
are not using a browser set for English and a Latin-based keyboard, your results
may vary):
1. Enter a lowercase letter “a”. Notice how the onKeyPress event handler shows
the charCode to be 97, which is the Unicode (and ASCII) value for the first of
the lowercase letters of the Latin alphabet. But the other two event types
record just the key’s code: 65.
2. Type an uppercase “A” via the Shift key. If you watch closely, you see that the
Shift key, itself, generates the key code 16 for the onKeyDown and onKeyUp
events. But the character key then shows the value 65 for all three events
(until you release the Shift key), because the ASCII value of the uppercase
letter happens to match the keyboard key code for that letter.
3. Press and release the Down Arrow key (be sure the cursor still flashes in the
TEXTAREA, because that’s where the keyboard events are being monitored).
As a non-character key, all three events stuff a value into the keyCode property,
but zero into charCode. The keyCode value for this key is 40.
4. Poke around with other non-character keys. Some may produce dialog boxes
or menus, but their key codes are recorded nonetheless.
(NN6) eventObject.charCode