上下选择 选到哪个里面字体就变色

Question

像这样这是 我的标签

Answer 1

 <script src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.4.2.min.js"></script>
<style>ul li.focus,ul li:hover{background:#f00;color:#fff}</style>
<ul id="ul">
    <li>1</li>
    <li>2</li>
    <li>3</li>
    <li>4</li>
    <li>5</li>
</ul>
<script>
    $(function () {
        var lis=$('#ul li'),focusLI,index,len=lis.length,up;
        $(document).keydown(function (e) {
            if (e.keyCode == 38 || e.keyCode == 40) {
                focusLI = lis.filter('.focus');
                up = e.keyCode == 38;
                if (focusLI.length == 0) index = up ? len - 1 : 0;
                else {
                    index = focusLI.index();
                    up ? index-- : index++;
                    if (index < 0) index = len - 1; else if (index >= len) index = 0;
                }
                lis.removeClass('focus').eq(index).addClass('focus')
            }
        });
    });
</script>