实现思路
Select 选择器 | Element Plus
1、select方法@visible-change这个方法是下拉框出现/隐藏时触发，当显示的时候将两个按钮插入到下拉框里面，是基于原生插入DOM的这种方式；
2、通过vue3 ref获取selectDOM，在获取select的popperPaneRef.$el （select下拉框的DOM），在基于js方法创建div `document.createElement('div')` 而div里面放入两个按钮使用div.appendChild插入按钮；
3、最后将div按钮插入到 popperPaneRef.$el（select下拉框的DOM）里就可以了，在将element-button-mini的css按钮样式复制，添加到原生按钮身上；
4、这里是无法使用el-button这种组件因为不解析，只能使用原生button，为其添加ele的样式；
具体实现看代码
<template>
<el-table :data="tableData" border style="width: 100%">
<el-table-column align="right" label="Date" prop="date" width="280">
<template #header>
<div class="headers-slot">
<p v-if="!isShowSelect"> Date <span @click="isShowSelect = !isShowSelect"> 🔍 </span> </p>
<div v-else>
🔍 <el-select
v-model="value3"
multiple
placeholder="Select"
style="width: 180px"
@visible-change="visibleChange"
ref="filterSelect"
>
<el-option
v-for="item in options"
:key="item.value"
:label="item.label"
:value="item.value"
/>
</el-select>
</div>
</div>
</template>
</el-table-column>
<el-table-column label="Name" prop="name" width="180"/>
<el-table-column label="Address" prop="address"/>
</el-table>
</template>
<script setup>
import {reactive, ref} from "vue";
const value3 = ref([])
const filterSelect = ref()
let isShowSelect = ref(false)
const options = reactive([
{
value: 'key-1',
label: '今天',
},
{
value: 'key-2',
label: '明天',
},
{
value: 'key-3',
label: '后天',
},
{
value: 'key-4',
label: '昨天',
},
{
value: 'key-5',
label: '前天',
},
])
let tableData = ref([
{
date: '今天',
name: 'Tom',
address: 'No. 189, Grove St, Los Angeles',
},
{
date: '明天',
name: 'Tom',
address: 'No. 189, Grove St, Los Angeles',
},
{
date: '后天',
name: 'Tom',
address: 'No. 189, Grove St, Los Angeles',
},
{
date: '昨天',
name: 'Tom',
address: 'No. 189, Grove St, Los Angeles',
},
{
date: '前天',
name: 'Tom222',
address: 'No. 189, Grove St, Los Angeles',
},
])
const visibleChange = (visible) => {
console.log(visible,filterSelect)
// 下拉框显示隐藏
if (visible ) {
const ref = filterSelect.value
// 拿到下拉选项的对象
let popper = ref.popperPaneRef
// 在拿到它的DOM元素
if (popper.$el) popper = popper.$el
// 判断是否有添加按钮
if (!Array.from(popper.children).some(v => v.className === 'select-btn-box')) {
// 插入按钮
let el = document.createElement('div')
let cancelBtn = document.createElement('button')
let confirmBtn = document.createElement('button')
el.className = 'select-btn-box'
cancelBtn.className = 'select-cancel-mini-btn'
confirmBtn.className = 'select-confirm-mini-btn'
cancelBtn.innerText = '取消'
confirmBtn.innerText = '确定'
el.appendChild(cancelBtn)
el.appendChild(confirmBtn)
// 调用确认和取消函数
cancelBtn.onclick = () => cancelHandle()
confirmBtn.onclick = () => confirmHandle()
popper.appendChild(el)
}
}
}
const cancelHandle = () => {
console.log('取消',value3.value)
isShowSelect.value = false
}
const confirmHandle = () => {
console.log('确认',value3.value)
isShowSelect.value = false
}
</script>
<style>
.headers-slot {
display: flex;
align-items: center;
justify-content: space-around;
}
/*
这些是按钮css，复制底层ele-btn-mini的
*/
.custom-button {
display: inline-block;
line-height: 1;
white-space: nowrap;
cursor: pointer;
background: #fff;
color: #fff;
-webkit-appearance: none;
text-align: center;
box-sizing: border-box;
outline: 0;
margin: 0;
padding: 10px 15px;
font-size: 14px;
border-radius: 4px;
}
.select-btn-box{
display: flex;
border-top: 1px solid #dfe6ec;
width: 100%;
height: 44px;
align-items: center;
justify-content:flex-end ;
}
.select-cancel-mini-btn{
display: inline-block;
display: inline-block;
line-height: 1;
white-space: nowrap;
cursor: pointer;
background: #FFFFFF;
border: 1px solid #DCDFE6;
border-color: #DCDFE6;
color: #606266;
-webkit-appearance: none;
text-align: center;
-webkit-box-sizing: border-box;
box-sizing: border-box;
outline: none;
margin: 0;
-webkit-transition: 0.1s;
transition: 0.1s;
font-weight: 400;
-moz-user-select: none;
-webkit-user-select: none;
-ms-user-select: none;
padding: 7px 15px;
font-size: 12px;
border-radius: 3px;
margin-right: 10px;
}
.select-cancel-mini-btn:hover{
background-color:#e4f2fe ;
color: #349cfb;
border-color: #afd9fd;
}
.select-confirm-mini-btn:hover{
background-color: #339bfa;
}
.select-confirm-mini-btn{
display: inline-block;
line-height: 1;
white-space: nowrap;
cursor: pointer;
background: #fff;
border: 1px solid #dcdfe6;
-webkit-appearance: none;
text-align: center;
box-sizing: border-box;
outline: none;
margin: 0;
transition: 0.1s;
font-weight: 500;
-moz-user-select: none;
-webkit-user-select: none;
-ms-user-select: none;
padding: 12px 20px;
font-size: 14px;
border-radius: 4px;
color: #fff;
background-color: #0080f5;
border-color: #409eff;
padding: 7px 15px;
font-size: 12px;
border-radius: 3px;
margin-right: 10px;
}
span{
cursor: pointer;
}
</style>
