element-plus/docs/examples/tree/accordion.vue

<template>
  <el-tree
    :data="data"
    :props="defaultProps"
    accordion
    @node-click="handleNodeClick"
  />
</template>

<script lang="ts">
export default {
  data() {
    return {
      data: [
        {
          label: 'Level one 1',
          children: [
            {
              label: 'Level two 1-1',
              children: [
                {
                  label: 'Level three 1-1-1',
                },
              ],
            },
          ],
        },
        {
          label: 'Level one 2',
          children: [
            {
              label: 'Level two 2-1',
              children: [
                {
                  label: 'Level three 2-1-1',
                },
              ],
            },
            {
              label: 'Level two 2-2',
              children: [
                {
                  label: 'Level three 2-2-1',
                },
              ],
            },
          ],
        },
        {
          label: 'Level one 3',
          children: [
            {
              label: 'Level two 3-1',
              children: [
                {
                  label: 'Level three 3-1-1',
                },
              ],
            },
            {
              label: 'Level two 3-2',
              children: [
                {
                  label: 'Level three 3-2-1',
                },
              ],
            },
          ],
        },
      ],
      defaultProps: {
        children: 'children',
        label: 'label',
      },
    }
  },
  methods: {
    handleNodeClick(data) {
      console.log(data)
    },
  },
}
</script>