code: function (container) {
      var tagName = container[0].tagName.toUpperCase()
      var scrollTop 
      if (tagName === 'BODY' || tagName === 'HTML') {
        scrollTop = container.scrollTop() || $(window).scrollTop()
      } else {
        scrollTop = container.scrollTop()
      }
      var offset = container.scrollHeight() - ($(window).height() + scrollTop)
      console.log(offset)
      return offset
    }
docs: fix https://github.com/lihongxun945/jquery-weui/issues/442 chrome will always return 0, when use document.body.scrollTop https://stackoverflow.com/questions/43717316/google-chrome-document-body-scrolltop-always-returns-0