代码如下：

//解决键盘弹出底部导航被顶上来的bug function focus_footer(h){
        window.onresize = function() {
          if (document.body.scrollHeight < h) {
            document.getElementById('footer').style.display = "none";       } else {
            document.getElementById('footer').style.display = "block";       }     }; }

 调用：

var h = document.body.scrollHeight;focus_footer(h);