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";
      }
    };
}

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