element plus 可选择树形组件(el-tree) 怎样一键展开/收起？实现方法详解

<el-button @click="takeall" style="height: 24px">
    {{zhanstatus % 2 != 0 ? "收起所有" : "展开所有"}}
</el-button>

<el-form-item label="可选择菜单" :label-width="formLabelWidth">
          <el-tree
            ref="folderTreeRef"
            :data="mneudata"
            show-checkbox
            node-key="id"
            highlight-current
            :props="defaultProps"
          />
        </el-form-item>

const folderTreeRef = ref(null);
const zhanstatus = ref(0);
let takeall = () => {
  zhanstatus.value++;
  if (zhanstatus.value % 2 == 0) {
    const nodes = folderTreeRef.value.store._getAllNodes();
    nodes.forEach(item => {
      item.expanded = false;
    });
  } else {
    const nodes = folderTreeRef.value.store._getAllNodes();
    nodes.forEach(item => {
      item.expanded = true;
    });
  };
};