以下Javascript代码为通过判断访问客户端的userAgent值，实现跳转到移动端首页index.html，供借鉴参考：

<script type="text/javascript">
  !function(){
    if(/phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone/i.test(navigator.userAgent.toLowerCase()) == true){
        location.href = '//chiji.qq.com/m/index.html';
    }
}();
</script>