JavaScript获取树型数据（数组）最深层级数

const treeObj = [{
  id: '0',
  name: '中国',
  children:[
    {
      id: '1',
      name:'湖北省',
      children:[
        {
          id: '1-1',
          name:'武汉市',
          children:[
            {
              id: '1-1-1',
              name:'武昌区',
            },        
          ]
        },    
      ]
    },
    {
      id: '2',
      name:'江苏省',
      children:[
        {
          id: '2-1',
          name:'南京市',
          children:[
            {
              id: '2-1-1',
              name:'玄武区',
            }   
          ]
        },    
        {
          id: '2-2',
          name:'镇江市',
          children:[
            {
              id: '2-2-1',
              name:'句容市',
              children: [
                {
                  id: '2-2-1-1',
                  name:'下蜀镇'
                },       
              ]
            },    
            {
              id: '2-2-2',
              name:'京口区'
            },    
          ]
        },       
      ]
    },
    {
      id: '3',
      name:'浙江省',
    }    
  ]
}];

function getMaxlevel (treeData) {
  let level = 0
  let v = this
  let maxLevel = 0
  function loop (data, level) {
    data.forEach(item => {
      item.level = level
      if (level > maxLevel) {
        maxLevel = level
      }
      if('children' in item){
        if (item.children.length > 0) {
          loop(item.children, level + 1)
        }
      }
    })             
  }
  loop(treeData,1)
  console.log(maxLevel)
}
getMaxlevel(treeObj)