如何阻止事件冒泡

<div onclick="showMsg(this,event)" id="outSide" style="width:100px; height:100px; background:#000; padding:50px"><div onclick="showMsg(this,event)" id="inSide" style="width:100px; height:100px; background:#CCC"></div></div><script type="text/javascript">//阻止事件冒泡后，你点击灰色盒子，整个过程只弹一次对话框了（注意与默认情况对比）function showMsg(obj,e){    alert(obj.id);    stopBubble(e)}//阻止事件冒泡函数function stopBubble(e){    if (e && e.stopPropagation)        e.stopPropagation()    else        window.event.cancelBubble=true}</script>