Untitled

<?PHP

    session_start();
    if(!isset($_SESSION['value'])) {
        $_SESSION['value'] = 0;
    }

    if(isset($_GET['action'])) {
        switch($_GET['action']) {
            case 'add':
                $_SESSION['value'] ++;
            break;
            case 'remove':
                $_SESSION['value'] --;
            break;
            case 'reset':
                $_SESSION['value']= 0;
            break;
        }

        header("Location: index.php");
        exit();
    }
?>

<html>
    <head>
        <title>Storing user values in session</title>
    </head>
    <body>
        <p>The current value is: <?PHP echo $_SESSION['value']; ?></p>

	<script>
		document.onkeyup = checkKey;

		function checkKey(e) {
			var location = '/index.php';
    			e = e || window.event;

    			if (e.keyCode == '13') {
				window.location = location + '?action=reset';
        			// up arrow
    			}
    			else if (e.keyCode == '38') {
				window.location = location + '?action=add';
        		// up arrow
    			}
    			else if (e.keyCode == '40') {
				window.location = location + '?action=remove';
        		// down arrow
    			}
    			else if (e.keyCode == '37') {
       			// left arrow
    			}
		        else if (e.keyCode == '39') {
       			// right arrow
    		}

	}
	</script>
    </body>
</html>