js递归实现树形目录

var data = [    {id: 1, name: "安徽", key: 1},    {id: 2, name: "江苏", key: 2},    {id: 3, name: "合肥", pid: 1, key: 3},    {id: 4, name: "庐阳区", pid: 3, key: 4},    {id: 5, name: "大杨镇", pid: 4, key: 5},    {id: 6, name: "南京", pid: 2, key: 6},    {id: 7, name: "玄武区", pid: 6, key: 7},    {id: 8, name: "梅园新村街道", pid: 7, key: 8},    {id: 9, name: "上海", key: 9},    {id: 10, name: "黄浦区", pid: 9, key: 10},    {id: 11, name: "外滩", pid: 10, key: 11},    {id: 12, name: "安庆", pid: 1, key: 12}];function sonsTree(obj, arr) {    var children = new Array();    for (var i = 0; i < arr.length; i++) {        if (arr[i].pid == obj.id) {  //pid等于加入数组            sonsTree(arr[i], arr);//递归出子元素            arr[i].pname=obj.name;            children.push(arr[i]);        }    }    if (children.length > 0) {        obj.children = children;    }    return obj;}function treeUtils() {    let ptree = [];    let tree = [];    for (var i = 0; i < data.length; i++) {        if (data[i].pid == null) {//获取父元素            let o = sonsTree(data[i], data);            ptree.push(o);        }    }    console.info(ptree);    return ptree;}