js通过a标签点击获取外面的li的id

Question

 "<ul>
<li id="a"><a>点击</a></li>
<li id="b"><a>提交</a></li>
</ul> "

怎么通过点击a标签获取li标签的id

Answer 1

 <ul id="ul">
    <li id="a"><a>点击</a></li>
    <li id="b"><a>提交</a></li>
</ul> 
<script>
    document.getElementById('ul').onclick = function (e) {
        e = e || window.event;
        var o = e.srcElement || e.target;
        if (o.tagName == 'A') alert(o.parentNode.id)
        else if(o.tagName=='LI') alert(o.id)
    }
</script>