false value for the key code argument.
Different scopes have different execution environments. This means that they have different built-ins
(different global object, different constructors, etc.). This may result in unexpected results. For instance,
 instanceof window.frames.Array will return
Array.prototype !== window.frames.Array
and arrays inherit from the former.
Note: just add another check if the current
event.type checking is insufficient.
Determine the actual printable character that is generated from a pressed key.
If the key does not correspond to a printable character,
undefined is returned.
The result may be altered by modifier keys.
Determine the pressed key of a keyboard event. This key should correspond to the physical key according
to a standard US keyboard layout. International keyboard layouts are handled by
keyIdentifier is used to access this deprecated field: