要求el-select支持多选，并增加全选和取消全选功能，缺点是提交的数据中会有全选这个字段

代码如下

<template>
    <div>全选功能</div>
    <el-select multiple collapse-tags v-model='selectedArray' @change='changeSelect' @remove-tag='removeTag'
      placeholder='请选择'>
      <el-option label='全选' value='全选' @click.native='selectAll'></el-option>
      <el-option v-for='(item, index) in options' :key='index' :label='item.name' :value='item.name'></el-option>
    </el-select>
</template>

<script lang="ts" setup>
import {ref} from 'vue'

const selectedArray = ref([])
const checked = ref(false)
const options = [
  { name: '哈哈哈', label: 'one' },
  { name: '好好好', label: 'tow' },
  { name: '你好', label: 'three' },
  { name: '嘎嘎', label: 'four' },
  { name: '么么么', label: 'five' }
]
const selectAll = () => {
  if (selectedArray.value.length<options.length) {
    selectedArray.value = []
    console.log(options)
    options.map((item) => {
      selectedArray.value.push(item.name)
    })
    selectedArray.value.unshift('全选')
  } else {
    selectedArray.value = []
  }
}
const changeSelect = (val) => {
  console.log(val)
  console.log(options,'1231')
  if (!val.includes('全选') && val.length === options.length) {
    selectedArray.value.unshift('全选')
  } else if (val.includes('全选') && (val.length - 1) < options.length) {
    selectedArray.value = selectedArray.value.filter((item) => {
      return item !== '全选'
    })
  }
}
const removeTag = (val) => {
  if (val === '全选') {
    selectedArray.value = []
  }
}
</script>

 multiple是实现下拉框多选的属性