css - 固定 div 随页面滚动

Question

是否可以使用 CSS 使固定的 div 在页面滚动时滚动？是的，由于其他原因，它需要保持固定。

.fixedDiv{
width:100%;
height:200px;
font-size:4em;
position:fixed;
}

.otherDiv{
position: relative;
width:250px;
height:auto;
}

<div class="fixedDiv">THIS IS A FIXED DIV</div>
<div class="otherDiv">The standard Lorem Ipsum passage, used since the 1500s
"Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."

Section 1.10.32 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"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?"

1914 translation by H. Rackham
"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 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat."

1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men who are so beguiled and demoralized by the charms of pleasure of the moment, so blinded by desire, that they cannot foresee the pain and trouble that are bound to ensue; and equal blame belongs to those who fail in their duty through weakness of will, which is the same as saying through shrinking from toil and pain. These cases are perfectly simple and easy to distinguish. In a free hour, when our power of choice is untrammelled and when nothing prevents our being able to do what we like best, every pleasure is to be welcomed and every pain avoided. But in certain circumstances and owing to the claims of duty or the obligations of business it will frequently occur that pleasures have to be repudiated and annoyances accepted. The wise man therefore always holds in these matters to this principle of selection: he rejects pleasures to secure other greater pleasures, or else he endures pains to avoid worse pains."
</div>

Answer 1

你需要听 onscroll 并在此基础上，更新固定元素相对于视口(viewport)的位置，并考虑滚动百分比(而不是其绝对值)和固定元素留下的可用垂直空间。

然后您可以使用 window.requestAnimationFrame 移动它和 transform: translate(0, <Y>) 获得更流畅、更高效的动画:

const fixedDiv = document.getElementById('fixedDiv');

document.onscroll = () => {
  const { documentElement } = document;
  const { scrollTop, scrollHeight, clientHeight } = documentElement;
  const availableSpace = clientHeight - fixedDiv.offsetHeight; 
  const scrollPercentage = scrollTop / (scrollHeight - clientHeight);
  
  /*
    scrollTop = How many pixels the page has scrolled vertically.
    scrollHeight = Total height of the page, including content that overflows the visible area.
    clientHeight = Viewport height.
    availableSpace = How much unused vertical space does #fixedDiv leave. 
  
    Using requestAnimationFrame and transform, rather than not using it and updating top or
    margin-top, will make the scrolling effect smoother and more performant:
  */
  
  requestAnimationFrame(() => {
    fixedDiv.style.transform = `translate(0, ${ availableSpace * scrollPercentage }px)`;
  });
};

body {
  margin: 0;
  font-family: monospace;
}

#fixedDiv {
  position: fixed;
  top: 0;
  z-index: 1;
  width: 100%;
  font-size: 32px;
  padding: 16px; 
  box-shadow: 0 2px 0 black, 0 -2px 0 black;
  background: rgba(255, 255, 255, .5);
}

#lorem {
  width: 250px;
  padding: 0 16px; 
}

<div id="fixedDiv">THIS IS A FIXED DIV</div>

<div id="lorem">
  <p>
  Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut porta vitae nunc ut fermentum. Nam cursus eu neque eu tincidunt. Praesent libero eros, pellentesque ut est id, consectetur vestibulum nisi. Nunc eget arcu tortor. Quisque tempus erat eros, ac interdum ligula ullamcorper luctus. Praesent ultricies tristique magna, non tempor quam porttitor eget. Vestibulum volutpat vel turpis eget auctor. Vestibulum sagittis odio pulvinar tortor vestibulum, sed pharetra lacus mollis. Mauris sollicitudin sem mi, quis placerat turpis commodo quis. Nam non blandit justo. Morbi cursus metus orci, efficitur condimentum purus vehicula vel. Sed vel pulvinar risus, at posuere mauris. Suspendisse a enim quis arcu porttitor finibus. Sed eu turpis iaculis, gravida quam non, hendrerit ipsum. Integer id commodo eros, sit amet tempus velit. Aliquam velit tortor, faucibus eu elit ut, volutpat pulvinar nisi.
  </p>
  <p>
  Quisque aliquam quam at orci tempor, sit amet suscipit mauris congue. Aenean id orci venenatis, iaculis nisi non, dictum mi. Duis a purus sed dui iaculis pharetra nec eu nunc. Ut tincidunt imperdiet felis, maximus dapibus sem congue ac. Nullam eget risus iaculis, blandit urna vel, dignissim tellus. Curabitur viverra, nisi eu blandit cursus, ante lacus maximus lacus, eget auctor ante ante id nibh. Vivamus interdum, ex ac placerat laoreet, tortor nisl efficitur elit, eu elementum felis ex ut magna. Vivamus tempor neque nec sodales consectetur. Suspendisse finibus tempor metus, varius euismod nulla. Cras maximus metus a viverra interdum. Duis sagittis mollis volutpat. Nulla lacinia ultricies scelerisque. Sed elementum sem eu suscipit pretium. Suspendisse potenti. Maecenas ut sollicitudin quam. Maecenas congue vehicula maximus.
  </p>
  <p>
  Sed dictum aliquam nibh vel facilisis. Donec nec erat ut justo pretium hendrerit at a ex. Aliquam sollicitudin nulla sed consectetur venenatis. Mauris facilisis nisl purus, sit amet tristique ligula sollicitudin sit amet. Donec non erat lorem. Praesent posuere ultricies fermentum. Donec rhoncus aliquet metus sed porttitor. Mauris semper nibh suscipit volutpat gravida. Morbi vulputate nulla eget convallis aliquet. Quisque velit dolor, finibus sed porttitor sit amet, dictum ac metus. Ut ultricies porttitor orci vel iaculis. In quis odio ornare, scelerisque lacus quis, auctor eros.
  </p>
  <p>
  Duis elementum, mauris eu facilisis porta, eros sem fermentum ex, in laoreet velit mauris sit amet massa. In nec ex euismod, ullamcorper magna quis, rutrum quam. Sed volutpat vel nisl quis placerat. Suspendisse auctor enim eu tempor congue. Quisque condimentum, ligula ut suscipit blandit, elit leo condimentum ante, auctor porttitor ante libero eu erat. Mauris et purus pulvinar, tristique leo eu, fermentum mauris. Suspendisse mollis vel odio a gravida. In euismod gravida massa. Donec in sem nunc. Etiam rutrum quis ex sed vestibulum. Nam aliquet tristique mi vel suscipit. Fusce et nisl et odio vulputate dignissim eget sed nisl.
  </p>
  <p>
  Integer non malesuada sapien, at tincidunt diam. Fusce id metus metus. In volutpat sem vel risus euismod vulputate. Pellentesque tincidunt ante nisi, id feugiat enim finibus a. Mauris scelerisque vestibulum nunc, scelerisque egestas mauris aliquet auctor. Nunc vel nulla molestie, tempor lacus sed, interdum sapien. Nam luctus quis tellus quis elementum. Donec lorem enim, semper consectetur massa quis, convallis vulputate lectus. Suspendisse ultricies ultricies orci, at molestie neque bibendum nec. Nullam hendrerit eget arcu vel laoreet. Praesent vestibulum leo sit amet libero venenatis, sit amet finibus lorem fermentum. Nullam quis tellus pulvinar, ultrices tellus nec, aliquet ante. Nam eu libero id orci volutpat egestas.
  </p>
</div>