详解iview的checkbox多选框全选时校验问题

<template>
  <div style="border-bottom: 1px solid #e9e9e9;padding-bottom:6px;margin-bottom:6px;">
    <Checkbox
      :indeterminate="indeterminate"
      :value="checkAll"
      @click.prevent.native="handleCheckAll">全选</Checkbox>
  </div>
  <CheckboxGroup v-model="checkAllGroup" @on-change="checkAllGroupChange">
    <Checkbox label="香蕉"></Checkbox>
    <Checkbox label="苹果"></Checkbox>
    <Checkbox label="西瓜"></Checkbox>
  </CheckboxGroup>
</template>
<script>
  export default {
    data () {
      return {
        indeterminate: true,
        checkAll: false,
        checkAllGroup: ['香蕉', '西瓜']
      }
    },
    methods: {
      handleCheckAll () {
        if (this.indeterminate) {
          this.checkAll = false;
        } else {
          this.checkAll = !this.checkAll;
        }
        this.indeterminate = false;

        if (this.checkAll) {
          this.checkAllGroup = ['香蕉', '苹果', '西瓜'];
        } else {
          this.checkAllGroup = [];
        }
      },
      checkAllGroupChange (data) {
        if (data.length === 3) {
          this.indeterminate = false;
          this.checkAll = true;
        } else if (data.length > 0) {
          this.indeterminate = true;
          this.checkAll = false;
        } else {
          this.indeterminate = false;
          this.checkAll = false;
        }
      }
    }
  }
</script>