链接

<html>
    <head>
        <meta charset=utf-8>
    </head>
    <body>
        <ul>
            <li>nowcoder</li>
        </ul>
    </body>
    <script type="text/javascript">
        // 补全代码
        let ans = function () {
            let li = document.querySelector('li')
            li.addEventListener('click', function (e) { //点击无效
                if (e && e.stopPropagation) {
                    //支持W3C的浏览器
                    e.stopPropagation()
                } else {
                   //IE中
                    window.event.cancelBubble = true;
                    }
                })
            }
        ans.call(this)
    </script>
</html>