题解 | dom 节点查找

        function commonParentNode(oNode1, oNode2) {
            if (oNode1.contains(oNode2)) {
                return oNode1
            } else if (oNode2.contains(oNode1)) {
                return oNode2;
            } else {
                return commonParentNode(oNode1, oNode2.parentNode);
            }
}