js修改父子json格式成树状结构格式

js修改父子json成树状结构

var json = [
  {
    "id" : "01",
    "pId":""
  }  ,
    {
    "id" : "01_01",
    "pId":"01"
  }  ,
    {
    "id" : "01_02",
    "pId":"01"
  }  ,
      {
    "id" : "01_02_01",
    "pId":"01_02"
  }  ,
  {
    "id" : "02",
    "pId":""
  },
    {
    "id" : "02-01",
    "pId":"02"
  },
      {
    "id" : "02-02",
    "pId":"02"
  },
  {
    "id" : "03",
    "pId":""
  },
  {
    "id" : "03_01",
    "pId":"03"
  }
];
function format(json){
    var ret = [], o = {};

    function add(arr, data){
        var obj = {
            "id": data.id,
            "pId": data.pId,
            "childer": []
        };
        o[data.id] = obj;
        arr.push(obj);
    }

    json.forEach(x => {
        if(o[x.pId]){
            add(o[x.pId].childer, x);
        }else{
            add(ret, x);
        }
    });

    return ret;
}
console.log(format(json));