<script type="text/javascript">
//监测手机端
function isMobile() {
  return /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent);
}
window.onload = function() { 
    //如果是手机设备
    if(isMobile()){
        ...
    }
}
</script>