iview/src/components/select/option-group.vue

<template>
    <li :class="[prefixCls + '-wrap']">
        <div :class="[prefixCls + '-title']">{{ label }}</div>
        <ul>
            <li :class="[prefixCls]"><slot></slot></li>
        </ul>
    </li>
</template>
<script>
    const prefixCls = 'ivu-select-group';

    export default {
        props: {
            label: {
                type: String,
                default: ''
            }
        },
        data () {
            return {
                prefixCls: prefixCls
            }
        }
    }
</script>