<el-tree :props="defaultParams"
               ref="tree"
               :data="treedata"
               show-checkbox
               node-key="id"
               @check-change="handleCheckChange">
      </el-tree>
    defaultParams: {
    label: 'name',
    children: 'childList'
  }
  handleCheckChange () {
  let res = this.$refs.tree.getCheckedNodes()
  let arr = []
  res.forEach((item) => {
    arr.push(item.id)
  })
},