随机显示 聊天数 有大用

<div class="footer">
    <ul>
        <li class="zxkc"><a href="{{ url('/categorys/16') }}" target="_blank"> <img src="{{ url('/assets/front/qiyetong/images/kc_03.png') }}" class="footer_1" alt="{{ $system_info->system_info_name }}_联系我们" title="联系我们"> <span>联系我们</span></a></li>
        <li class="zxkc"><a href="mqqwpa://im/chat?chat_type=wpa&uin={{ trim($contact->contact_qq) }}&version=1&src_type=web" ><img src="{{ url('/assets/front/qiyetong/images/zx_03.png') }}" class="footer_1" alt="{{ $system_info->system_info_name }}_在线咨询" title="{{ $system_info->system_info_name }}_在线咨询"><span>在线咨询</span><p id="zxzx">30</p></a></li>
        <li class="zxkc"><a href="tel:{{ $contact->contact_bodadianhua }}" target="_blank"><img src="{{ url('/assets/front/qiyetong/images/dh_03.png') }}" class="footer_1" alt="{{ $system_info->system_info_name }}_电话咨询" title="{{ $system_info->system_info_name }}_电话咨询"><span>电话咨询</span></a></li>
        <li class="db"><a href="#totop" target="_self"><img src="{{ url('/assets/front/qiyetong/images/db_03.png') }}" class="footer_2" alt="返回顶部" title="返回顶部"></a></li>
    </ul>
</div>
<script>
    zxzx = document.getElementById('zxzx');
    var timmer = null;
    clearInterval(timmer);
    timmer = setInterval(function(){
        zxzx.innerHTML=Math.round(Math.random()*11)+20;
    },2000);
</script>