反向过渡不适用于导航

如何解决反向过渡不适用于导航

我已根据位置构建了一个过渡。在反向滚动中，我通过JS添加了 .scroll-stick-nav 类，并在滚动淹没时将其删除。班级出现时过渡有效，但班级消失则时间过渡无效。导航突然消失，没有任何过渡。下面的代码。

var position = $(window).scrollTop();
$(window).scroll(function() {
  var scroll = $(window).scrollTop();

  if ($('#cst-navbar').length > 0) {
    //if its cst landing page
    if (scroll > position) {
      $(".navbar").removeClass("scroll-stick-nav");
      $(".navbar").addClass("smooth-scroll");
    } else if (scroll < 100) {
      $(".navbar").removeClass("scroll-stick-nav");
      $(".navbar").removeClass("smooth-scroll");
    } else {
      $(".navbar").addClass("scroll-stick-nav");
      $(".navbar").removeClass("smooth-scroll");
    }
    position = scroll;
  } else {
    //if its other internal pages
    if (scroll > 0) {
      $(".navbar").addClass("scroll-stick-nav");
    } else {
      $(".navbar").removeClass("scroll-stick-nav");
    }
  }
});

* {
  margin: 0;
}

p {
  font-size: 25px;
  margin-bottom: 30px;
}

.navbar {
  background-color: orange;
  padding: 20px;
  transition: top .2s linear !important;
}

.scroll-stick-nav {
  position: fixed !important;
  width: 100%;
  top: 0;
}

.smooth-scroll {
  top: -63px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="cst-navbar">
  <header class="navbar">
    navigation
  </header>

  <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s,when an unknown printer took a galley of type and scrambled it to make a type specimen book. It
    has survived not only five centuries,but also the leap into electronic typesetting,remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages,and more recently with desktop
    publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>
  <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s,and more recently with desktop
    publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>

  <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s,and more recently with desktop
    publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>
</div>

解决方法

您只需将position: fixed和width: 100%移到.navbar类中，这样唯一的过渡就是top值。并以类.scroll-stick-nav开始该元素，因此在加载时它始终停留在顶部。

我还删除了您的JQuery中检查滚动是否小于100的部分，因为如果用户向上滚动，它将始终显示导航栏。

var position = $(window).scrollTop();
$(window).scroll(function() {
  var scroll = $(window).scrollTop();

  if ($('#cst-navbar').length > 0) {
    //if its cst landing page
    if (scroll > position) {
      $(".navbar").removeClass("scroll-stick-nav");
      $(".navbar").addClass("smooth-scroll");
    } else {
      $(".navbar").addClass("scroll-stick-nav");
      $(".navbar").removeClass("smooth-scroll");
    }
    position = scroll;
  } else {
    //if its other internal pages
    if (scroll > 0) {
      $(".navbar").addClass("scroll-stick-nav");
    } else {
      $(".navbar").removeClass("scroll-stick-nav");
    }
  }
});

* {
  margin: 0;
}

p {
  font-size: 25px;
  margin-bottom: 30px;
}

.navbar {
  position: fixed !important;
  width: 100%;
  background-color: orange;
  padding: 20px;
  transition: top .2s linear !important;
}

.scroll-stick-nav {
  top: 0;
}

.smooth-scroll {
  top: -63px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="cst-navbar">
  <header class="navbar scroll-stick-nav">
    navigation
  </header>

  <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s,when an unknown printer took a galley of type and scrambled it to make a type specimen book. It
    has survived not only five centuries,but also the leap into electronic typesetting,remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages,and more recently with desktop
    publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>
  <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s,and more recently with desktop
    publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>

  <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s,and more recently with desktop
    publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>
</div>