请问怎样用js实现点击图片出现播放图片 再点击出现暂停图片？

Question

<style>

body{background:#999;}

.box{width:100px; height:100px; -webkit-border-radius:50px; background:#FFF; position:relative;}

#img1{position:absolute; top:25px; left:25px; display:block;  }

#img2{position:absolute; top:25px; left:25px; display:none;}

</style>

<div class="box" onclick="click()";>

<img src="../web/images/zt.png" id="img1" style="width:50px; height:50px;" />

    <img src="../web/images/ks.png" id="img2" style="width:50px; height:50px;" />

</div>