<a data-toggle="modal" href="#myModal_devices" id="check_devices" class="guide_s step1 ok" onclick="GetLanHosts();return false;"><span>►</span>已有<em>0</em>台设备连接</a>

if(client_num!=undefined)
{
document.getElementById('check_devices').innerHTML="<span>►</span>已有<em>"+client_num+"</em>台设备连接";
document.getElementById('client_num').innerHTML='目前已有'+client_num+'台设备连接';
}