<body>
<div class="arr">
<img src="arr-down.png" >
</div>
<script src="js/jquery.js"></script>
<script>
var $arr = $(‘.arr‘);
var target = false;
$arr.click(function () {
target = !target;
if (target) {
$arr.find(‘img‘).attr(‘src‘, ‘arr-up.png‘);
} else {
$arr.find(‘img‘).attr(‘src‘, ‘arr-down.png‘);
}
});
</script>
</body>
原文：http://www.cnblogs.com/jiaoyue/p/7384600.html