Sys.UI.DomEvent charCode Field
Gets the character code of the key that raised the associated keyPress event.
Use the charCode field to get the character code of a pressed key or key combination that raised a keyPress event. The keyPress event provides a single character code that identifies key combinations. The keyPress event is not raised for single modifier keys such as ALT, CTRL, and SHIFT.
To get the key code of each key that was pressed to raise a keyUp or keyDown event, use the Sys.UI.DomEvent.keyCode field instead of the charCode field. The keyUp or keyDown events are raised for every key, even modifier keys such as ALT, CTRL, and SHIFT. For key combinations such as CTRL+Z, the keyCode field reflects whichever key first raised the keyUp or keyDown event.