递归法找到最近的公共父节点

function commonParentNode(oNode1, oNode2) {

    return recur_find(oNode1.parentNode,oNode2.parentNode)

    function recur_find(parent1,parent2){
        if(parent1.contains(oNode2)){
            return parent1
        }
        if(parent2.contains(oNode1)){
            return parent2
        }
        recur_find(parent1.parentNode,parent2.parentNode)
    }

}