如何选择图片里的alt值,希望知道的朋友,给指点一下
html 代码:     <a href="#" class="nl_ico"><img alt="系统设置" src="images/computer.png" width="32" height="32" /></a>
     <a class="nl_ico" href="#"><img src="images/computer.png" width="32" height="32" /></a>
     <a class="nl_ico" href="#"><img alt="312321" src="images/computer.png" width="32" height="32" /></a>
     <a class="nl_ico" href="#"><img alt="sadfsdf" src="images/computer.png" width="32" height="32" /></a>
     <a class="nl_ico" href="#"><img alt="在城城城" src="images/computer.png" width="32" height="32" /></a>
     <a class="nl_ico" href="#"><img alt="伯傜傜" src="images/computer.png" width="32" height="32" /></a>
     <a class="nl_ico" href="#"><img alt="平步青云" src="images/computer.png" width="32" height="32" /></a>
     <a class="nl_ico" href="#"><img alt="傜楏先入为主和和" src="images/computer.png" width="32" height="32" /></a>jQUERY 代码:<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script type="text/javascript">
$(".nl_ico").mousemove(function(){
alert($(this).attr("alt"));

})
</script>为什么选取的值是空呢?大侠帮我指正一下啊javascriptalt