根据固定 div 当前结束的内容更改背景颜色

Question

我有一个固定位置的导航栏，会有不同背景颜色的 div。 滚动时，我希望我的导航具有与结束的 div 相同的颜色。

我的目标是当滚动另一个 div 的内容不与这样的导航栏内容重叠时

Answer 1

您可以通过检查滚动事件中哪个元素处于活动状态来使用 javascript 更改导航栏背景，我将在此处发布一个使用 jquery 的简单解决方案，但是您可以使用一些 React 依赖项，它为您提供基于滚动更改的活动元素颜色，构建自定义钩子也是解决您的用例的不错选择：

$(window).scroll(function() {
    const scrollDistance = $(window).scrollTop();
    $('section').each(function(i) {
        if ($(this).position().top <= scrollDistance) {
            const bgColor = `linear-gradient(#ccc, ${$(this).css('background-color')})`;
            $('nav').css('background', bgColor);
        }
    });
});

*{
   box-sizing: border-box;
}
.container{
  width: 400px;
  position: relative;
}
section, nav{
  padding: 1rem;
}
section{
    padding-top: 40px;
}
nav{
  position: fixed;
  top: 0;
  display: block;
  background: transparent;
  font-weight: 600;
  width: 400px;
}
.first-section{
  background: yellow;
} 
.second-section{
  background: #ccc;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="container">
<nav>Navigation</nav>
<section class="first-section">
    Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?
</section>

<section class="second-section">
But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?
</section>
  
  <section class="first-section">
    Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?
</section>
</div>