Jquery 在添加/删除类之前添加额外的160px？

在添加和删除类之前，我正在尝试添加额外的160px

原始工作jQuery：

$.fn.isInViewport = function() {
  let elementTop = $(this).offset().top;
  let elementBottom = elementTop + $(this).outerHeight();
  let viewportTop = $(window).scrollTop();
  let viewportBottom = viewportTop + $(window).height();
  return elementBottom > viewportTop && elementTop < viewportBottom;
};

$(window).scroll(function() {
  if ($('#main-header').isInViewport()) {
    $('#main-menu').removeClass('hide');
  } else {
    $('#main-menu').addClass('hide');
  }
});

// own custom jQuery function
$.fn.isInViewportWithMargin = function(px) {
  let elementTop = $(this).offset().top - px;
  let elementBottom = elementTop + ( $(this).outerHeight() + px*2 );
  let viewportTop = $(window).scrollTop();
  let viewportBottom = viewportTop + $(window).height();
  return elementBottom > viewportTop && elementTop < viewportBottom;
};

$(window).scroll(function() {
  if ($('#main-header').isInViewportWithMargin(160)) {
    $('#main-menu').removeClass('hide');
  } else {
    $('#main-menu').addClass('hide');
  }
});

尝试扩展jQuery：

$.fn.isInViewport = function() {
  let elementTop = $(this).offset().top;
  let elementBottom = elementTop + $(this).outerHeight();
  let viewportTop = $(window).scrollTop();
  let viewportBottom = viewportTop + $(window).height();
  return elementBottom > viewportTop && elementTop < viewportBottom;
};

$(window).scroll(function() {
  if ($('#main-header').isInViewport()) {
    $('#main-menu').removeClass('hide');
  } else {
    $('#main-menu').addClass('hide');
  }
});

// own custom jQuery function
$.fn.isInViewportWithMargin = function(px) {
  let elementTop = $(this).offset().top - px;
  let elementBottom = elementTop + ( $(this).outerHeight() + px*2 );
  let viewportTop = $(window).scrollTop();
  let viewportBottom = viewportTop + $(window).height();
  return elementBottom > viewportTop && elementTop < viewportBottom;
};

$(window).scroll(function() {
  if ($('#main-header').isInViewportWithMargin(160)) {
    $('#main-menu').removeClass('hide');
  } else {
    $('#main-menu').addClass('hide');
  }
});

//自己的自定义jQuery函数
$.fn.isInViewportWithMargin=函数（px）{
让elementTop=$（this）.offset（）.top-px；
让elementBottom=elementTop+（$（this）.outerHeight（）+px*2）；
让viewportTop=$（窗口）.scrollTop（）；
让viewportBottom=viewportTop+$（window）.height（）；
返回elementBottom>viewportTop&&elementTop

谢谢您的帮助。