el-select 结合 el-checkBox 实现下拉全选+多选功能

实现效果如图所示：

具体代码如下：

<!--
 * @Description: el-select 结合 el-checkBox 实现下拉全选+多选功能
-->
<template>
    <div style="padding: 300px 100px;">
        <el-select v-model="menus" multiple collapse-tags @change="changeSelectMenu" placeholder="请选择菜单" clearable >
            <el-checkbox v-model="checkedAll" @change="selectAll">全选</el-checkbox>
            <el-option v-for="item in menuList" :key="item.id" :label="item.menuName" :value="item.id"></el-option>
        </el-select>
    </div>
</template>
<script>
export default{
    data() {
        return {
            checkedAll: false,
            menus: [],
            menuList: [
                {id: '01', menuName: '菜单一'},
                {id: '02', menuName: '菜单二'},
                {id: '03', menuName: '菜单三'},
                {id: '04', menuName: '菜单四'},
                {id: '05', menuName: '菜单五'},
                {id: '06', menuName: '菜单六'},
            ]
        };
    },
    mounted(){

    },
    methods:{
        // 点击下拉列表选项时触发
        changeSelectMenu(val) {
            if(val.length === this.menuList.length){
                this.checkedAll = true;
            }else{
                this.checkedAll = false;
            }
        },
        // 点击“全选”按钮时触发
        selectAll() {
            this.menus = [];
            if(this.checkedAll){
                this.menuList.map(item => {
                    this.menus.push(item.id);
                })
            }else{
                this.menus = [];
            }
        }
    }
}
</script>
<style lang='scss'>
    .el-select-dropdown {
        .el-checkbox {
            display: inline-block;
            margin-left: 20px;
            padding: 8px 0;
        }
    }
</style>