grabbing barcode reader

HTML

<ul id="codes">
    <li>NICK</li>
    <li>CLARKSON</li>
</ul>

JavaScript

// lock scopell
    // init empty string to hold current code
    var str = '';
    // bind to key down event
    $(window).keydown(function(e) {
        // get character from keycode ( always uppercase )
        var key = String.fromCharCode(e.keyCode);
        // is current key enter?
        if (e.keyCode == 13) {
            // try and find code in current list and identify
            if ($('#codes li:contains(' + str + ')').css({
                'background': 'red'
            }).length == 0) {
                // if not in list append it
                $('<li>' + str + '</li>').appendTo('#codes').css({
                    'background': 'green'
                });
            }
            // empty string in preparation for net code
            str = '';
        } else {
            // concat string until enter is pressed    
            str += key;
        }
    })
})();