How is the event.keyCode used in JavaScript?

In JavaScript, the event.keyCode property is used to obtain the Unicode encoding of the key that triggered the event. It is commonly used to handle keyboard events such as keydown or keyup events.

You can use event.keyCode to determine which key the user has pressed or released. Each key has a unique corresponding Unicode value. By checking the value of event.keyCode, you can identify which key has been pressed or released.

Here are the keyCode values for some common keys:

1. Direction keys: Up (38), Down (40), Left (37), Right (39)
2. Function keys: Enter (13), Esc (27), Spacebar (32)
3. Alphabetic and numeric keys: A-Z (65-90), 0-9 (48-57)

It is important to note that the event.keyCode property has been deprecated in some newer browsers, and instead the event.key property should be used. It is recommended to use event.key to obtain the value of the pressed key, rather than event.keyCode. However, if backward compatibility with older browsers is needed, event.keyCode can still be used.