为什么checkList类型打印出来是object?

Question

<template>
  <div>
        <ul>
            <li class="bookItem" v-for="item in bookList" :key="item.id" style="text-align: left;">
               <el-checkbox v-model="item.checked" @change="handleChecked(item)">
                <img class="bookImg" :src='item.book_url' style="width: 100px; height: 100px;">
                <h3>{{item.book_title}}</h3>
                <span class="price">￥{{item.book_price}}</span>
                <div @click.stop="func">
                      <el-input-number v-model="item.num" size="small" @change="handleChange" :min="1"></el-input-number> 
                  </div>
                </div>
            </el-checkbox>
            </li>
        </ul>
      </keep-alive>
      
      <div class="cart">
          <span>共</span>
          <span class="highLight">{{mount}}</span>
          <span>本</span>
          <el-button type="primary" @click.native="onOrder" :disabled="disable"><router-link :to="{name:'Money',params:{data:this.sel}}">提交订单</router-link></el-button>
          <!-- <el-button type="primary" @click.stop="onOrder"><router-link to="/book/bookMoney">提交订单</router-link></el-button> -->
      </div>
  </div>
 </template>
<script> 
export default {
  data () {
    return {
    checkAll: false,
    isIndeterminate: true,
    breadCrumbList: [],
    bookList: [],
    radio: '0',
    checkList: [],
    num: 1,
    mount: 0,
    total: 0,
    sel: [],
    clickFlag: false,
    disable: true
    }
  },
  mounted () {
    window.localStorage.checkList = '[object Object]'
    this.bookList = [{
    id: '0',
    book_url: require('../assets/images/book1.jpg'),
    book_title: '古埃及死者之书',
    book_price: '39',
    num: 0,
    checked: false
    },{
    id: '1',
    book_url: require('../assets/images/book2.jpg'),
    book_title: '当你开始爱自己',
    book_price: '45',
    num: 0,
    checked: false
    },{
    id: '2',
    book_url: require('../assets/images/book3.jpg'),
    book_title: '格雷巴旅馆',
    book_price: '59',
    num: 0,
    checked: false
    }]
  },
  methods: {
    func () {
    },
    handleChecked (val) {
      //保存选中的checkbox的id
      console.log(typeof this.checkList) //为什么打印出来是object?
      if (this.checkList.indexOf(val.id) == -1)
        this.checkList.push(val.id)
      //设置提交订单按钮的禁用与否
      if (this.checkList.length > 0)
        this.disable = false

      //勾选checkbox所需要做的事情
      if (val.checked === true) {
        console.log(66)
        this.mount += Number(val.num)
      } else {
        console.log(this.checkList)
         console.log(typeof this.checkList)
        // this.checkList.remove(val.id)
        this.mount -= Number(val.num)
      }
      //将所选checkbox的id保存到localStorage
      window.localStorage.setItem('checkList',JSON.stringify(this.checkList))
    },
  
</script>

Answer 1

数组使用typeof打出来就是object的，你要查看对象是否为数组，可以使用Array.isArray

Answer 2

数组不就是object吗？ 有什么问题。。。又没有叫Array的数据类型、
另外localStorage只能保存字符串，所以用JSON.stringify转为字符串、JSON.parse转为对象是可以的。