<first-menu>
    <menu-item href="/dashboard/boards" code="index">概况</menu-item>
    <menu-item href="/dashboard/boards/waf" code="waf">WAF</menu-item>
    <menu-item href="/dashboard/boards/dns" code="dns">DNS</menu-item>
    <menu-item href="/dashboard/boards/user" code="user">用户</menu-item>
    <menu-item href="/dashboard/boards/events" code="event">事件<span :class="{red: countEvents > 0}">({{countEvents}})</span></menu-item>
</first-menu>