Keylistener in Javascript
Here's an update for modern browsers in 2019
let playerSpriteX = 0;document.addEventListener('keyup', (e) => { if (e.code === "ArrowUp") playerSpriteX += 10 else if (e.code === "ArrowDown") playerSpriteX -= 10 document.getElementById('test').innerHTML = 'playerSpriteX = ' + playerSpriteX;});Click on this window to focus it, and hit keys up and down<br><br><br><div id="test">playerSpriteX = 0</div>Original answer from 2013
window.onkeyup = function(e) { var key = e.keyCode ? e.keyCode : e.which; if (key == 38) { playerSpriteX += 10; }else if (key == 40) { playerSpriteX -= 10; }}
The code is
document.addEventListener('keydown', function(event){ alert(event.keyCode);} );This return the ascii code of the key. If you need the key representation, use event.key (This will return 'a', 'o', 'Alt'...)
If you don't want the event to be continuous (if you want the user to have to release the key each time), change onkeydown to onkeyup
window.onkeydown = function (e) { var code = e.keyCode ? e.keyCode : e.which; if (code === 38) { //up key alert('up'); } else if (code === 40) { //down key alert('down'); }};