Java Reference
In-Depth Information
means that it's the most reliable way to find out the character that was pressed on
the keyboard.
3. The
keyup
event occurs when a key is released.
To understand the differences in these events, it is important to distinguish between a phys-
ical
key
on the keyboard and a
character
that appears on the screen. The
keydown
event
is the action of pressing a key, whereas the
keypress
event is the action of a character
being typed on the screen.
To see an example of this add the following to scripts.js:
addEventListener("keydown",highlight);
Pressing a key will result in the whole document changing color., because the event listener
was applied to the whole document. If you hold a key down, the event will continue to fire,
creating a psychedelic effect on the page.
To see the
keyup
event working, add the code that uses an anonymous function to show
the exact time the key was released in the console:
addEventListener("keyup", function stop(event){
var date = new Date;
console.log("You stopped pressing the key on " + date);
});
The
keydown
and
keyup
event objects both have an
event.keyCode
property that
returns a numerical code that represents the key that fired the event; for example, the
J
key
has a key code of 74. You can find the
code for each key on the JavaScript key code page.
The
keypress
event object has an
event.charCode
property that returns a numerical
Unicode character code representing the character that will be shown on the screen.
These two properties are similar, but not the same. For example, on a UK keyboard, press-
ing the
3
key results in a
keyCode
of 51 and a
charCode
of 51. But if the
Shift
key is
held down while 3 is pressed the
charCode
will be 163, but the
keyCode
will still be
51.
