目標是構建一個多層級的JSON[             {                name: "A_root",                id:1,                depth:0,                child: [                     {                        name: "a1_1",                        depth:1,                        id:1                     },                     {                        name: "a1_2",                        depth:1,                        id:2                     }                 ]             },             {                 name: "B_root" ,                 id:2,                 depth:0                                  }         ]用一個函數在任意地方添加節點比如可以在depth:0的這一級新增一個{name:'C_root',id:3,depth:0}也可以在depth:0 id:2這里增添一個子節點構建成{ name:'B_root',id:2,depth:0,child:[{name:"b1_1",id:1,depth:1}] }以此類推新增子節點，因為可能在任意位置新增節點所以希望能用一個函數解決