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

<template>
  <el-tree
    ref="tree"
    :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">
export default {
  data() {
    return {
      data: [
        {
          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',
            },
          ],
        },
      ],
      defaultProps: {
        children: 'children',
        label: 'label',
      },
    }
  },
  methods: {
    getCheckedNodes() {
      console.log(this.$refs.tree.getCheckedNodes())
    },
    getCheckedKeys() {
      console.log(this.$refs.tree.getCheckedKeys())
    },
    setCheckedNodes() {
      this.$refs.tree.setCheckedNodes([
        {
          id: 5,
          label: 'Level two 2-1',
        },
        {
          id: 9,
          label: 'Level three 1-1-1',
        },
      ])
    },
    setCheckedKeys() {
      this.$refs.tree.setCheckedKeys([3])
    },
    resetChecked() {
      this.$refs.tree.setCheckedKeys([])
    },
  },
}
</script>