遍历树结构删除长度没有的children

treeFun(data){ //遍历树结构删除长度没有的children
      return data.map(item =>{
        if(item.children.length > 0){
          this.treeFun(item.children)
        }else{
          delete item.children
        }
        return item
      })
    }

this.$http.get(`${host}/api/areas/tertiary`).then((res) => {
    this.column = this.treeFun(res.data)
});