Jq 手机端输入框防止底部菜单被小键盘弹起

var winHeight = $(window).height();  //获取当前页面高度
$(window).resize(function () {
  var thisHeight = $(this).height();
  if ( winHeight - thisHeight > 140 ) {
    //键盘弹出
    $('.footer').css('position','static');
  } else {
    //键盘收起
    $('.footer').css({'position':'fixed','bottom':'0'});

  }
})