e.which
e.which
is not an event, which
is a property of the event
object, which most people label as e
in their event handlers. It contains the key code of the key which was pressed to trigger the event (eg: keydown, keyup).
document.onkeypress = function(myEvent) { // doesn't have to be "e"
console.log(myEvent.which);
};
With that code, the console will print out the code of any key you press on the keyboard.