后台我拿的数据是这样的格式: [ {id:1 , parentId: 0, name: '', level: 0}, {id:2 , parentId: 0, name: '', level: 0}, {id:3 , parentId: 2, name: '', level: 1}, {id:4 , parentId: 2, name: '', level: 1}, {id:5 , parentId: 4, name: '', level: 2}, ] 转换后的数据差不多就是这样的格式 { […