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

<template>
  <el-tree
    ref="treeRef"
    :data="data"
    show-checkbox
    default-expand-all
    node-key="id"
    highlight-current
    :props="defaultProps"
  />

  <div class="buttons">
    <el-button @click="getCheckedNodes">get by node</el-button>
    <el-button @click="getCheckedKeys">get by key</el-button>
    <el-button @click="setCheckedNodes">set by node</el-button>
    <el-button @click="setCheckedKeys">set by key</el-button>
    <el-button @click="resetChecked">reset</el-button>
  </div>
</template>

<script lang="ts" setup>
import { ref } from 'vue'
import type { ElTree } from 'element-plus'
import type Node from 'element-plus/es/components/tree/src/model/node'

interface Tree {
  id: number
  label: string
  children?: Tree[]
}

const treeRef = ref<InstanceType<typeof ElTree>>()

const getCheckedNodes = () => {
  console.log(treeRef.value!.getCheckedNodes(false, false))
}
const getCheckedKeys = () => {
  console.log(treeRef.value!.getCheckedKeys(false))
}
const setCheckedNodes = () => {
  treeRef.value!.setCheckedNodes(
    [
      {
        id: 5,
        label: 'Level two 2-1',
      },
      {
        id: 9,
        label: 'Level three 1-1-1',
      },
    ] as Node[],
    false
  )
}
const setCheckedKeys = () => {
  treeRef.value!.setCheckedKeys([3], false)
}
const resetChecked = () => {
  treeRef.value!.setCheckedKeys([], false)
}

const defaultProps = {
  children: 'children',
  label: 'label',
}

const data: Tree[] = [
  {
    id: 1,
    label: 'Level one 1',
    children: [
      {
        id: 4,
        label: 'Level two 1-1',
        children: [
          {
            id: 9,
            label: 'Level three 1-1-1',
          },
          {
            id: 10,
            label: 'Level three 1-1-2',
          },
        ],
      },
    ],
  },
  {
    id: 2,
    label: 'Level one 2',
    children: [
      {
        id: 5,
        label: 'Level two 2-1',
      },
      {
        id: 6,
        label: 'Level two 2-2',
      },
    ],
  },
  {
    id: 3,
    label: 'Level one 3',
    children: [
      {
        id: 7,
        label: 'Level two 3-1',
      },
      {
        id: 8,
        label: 'Level two 3-2',
      },
    ],
  },
]
</script>