SOURCE

let oUl =document.querySelector("ul")
        oUl.onclick = function(ev){
            let oEvent = ev || window.event;
            let target = oEvent.target || oEvent.srcElement;
            if(target.nodeName.toLowerCase()==='li') {
                alert(target.innerHTML)
            }
        }

<ul>
        <li>哈哈</li>
        <li>苹果</li>
        <li>香蕉</li>
        <li>橘子</li>
        <p>海豚</p>
        <li>橙子</li>
        <p>其他水果</p>
    </ul>

*{margin: 0;padding: 0}
    ul{width: 200px; margin: 0 auto;}
    li,p{list-style: none; border: 1px solid #000; margin-top: 10px;}