// 部门树形排列
result.data.forEach(item => {
  this.creatTree(item, arr);
});
console.log(arr);
      
// 生成部门树
creatTree (meta, list) {
    let index = list.findIndex(ret => ret.treeId === meta.treeParentId);
    if (index > -1) {
        list[index].children.push(meta);
    } else if (meta.treeParentId === 'department_0') {
        list.push(meta);
    } else {
        list.forEach(item => {
            item.children && item.children.length && this.creatTree(meta, item.children)
        });
    }
},

// 树转平 this.treeToList(list, 'items');
treeToList (tree, field) {
  let arr = [];
  tree && tree.forEach(item => {
    if (item[field].length) arr.push(...this.treeToList(item[field], field));
    item[field] = [];
    arr.push(item);
  });

  return arr;
}