elementui table 添加tooltip

<el-table
    :data="item.answer"
>
    <el-table-column
        prop="name"
        label="選項"
    >
    </el-table-column>
    <el-table-column
        prop="count"
        label="平均得分"
        :render-header="renderHeader"
    >
    </el-table-column>
    <el-table-column
        prop="ratio"
        label="占比"
    >
    </el-table-column>
</el-table>

<script>
export default {
    methods: {
        renderHeader() {
            return (
                <div style="display:inline;">
                    <el-tooltip class="tooltip" effect="dark" placement="right">
                        <i class="el-icon-question">平均得分</i>
                        <div slot="content" >平均得分是多少？</div>
                    </el-tooltip>
                </div>
            );
        },
    },
}
</script>