语言►CSS

CSS中的sticky定位

本文作者: jsweibo

本文链接: https://jsweibo.github.io/2020/03/28/CSS%E4%B8%AD%E7%9A%84sticky%E5%AE%9A%E4%BD%8D/

摘要

本文主要讲述了：

  1. 效果

正文

效果

首先想象元素是static定位：

  • 当元素距离 viewport 指定边界的距离大于等于指定的值时，表现得像是static定位
  • 当元素距离 viewport 指定边界的距离小于指定的值时，表现得像是特殊的relative定位。之所以说特殊，是因为sticky定位会使得元素黏在 viewport 上（就像fixed定位那样）。黏性定位也由此得名

示例：一进入页面表现得像是static定位，滚动后表现得像是特殊的relative定位

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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1 class="sticky">hello, jsweibo</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <style>
      .sticky {
        position: -webkit-sticky;
        position: sticky;
        top: 100px;
        background-color: #639;
        color: #fff;
      }
    </style>
    <script>
      window.addEventListener('load', function () {
        console.log(document.querySelector('.sticky').getBoundingClientRect());
        console.log(
          Number.parseInt(
            getComputedStyle(document.querySelector('.sticky')).top,
            10
          )
        );
      });
      window.addEventListener('scroll', function () {
        console.log(document.querySelector('.sticky').getBoundingClientRect());
        console.log(
          Number.parseInt(
            getComputedStyle(document.querySelector('.sticky')).top,
            10
          )
        );
      });
    </script>
  </body>
</html>

示例：一进入页面表现得像是特殊的relative定位，滚动后仍表现得像是特殊的relative定位

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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1 class="sticky">hello, jsweibo</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <h1>jsweibo.github.io</h1>
    <style>
      .sticky {
        position: -webkit-sticky;
        position: sticky;
        top: 400px;
        background-color: #639;
        color: #fff;
      }
    </style>
    <script>
      window.addEventListener('load', function () {
        console.log(document.querySelector('.sticky').getBoundingClientRect());
        console.log(
          Number.parseInt(
            getComputedStyle(document.querySelector('.sticky')).top,
            10
          )
        );
      });
      window.addEventListener('scroll', function () {
        console.log(document.querySelector('.sticky').getBoundingClientRect());
        console.log(
          Number.parseInt(
            getComputedStyle(document.querySelector('.sticky')).top,
            10
          )
        );
      });
    </script>
  </body>
</html>

参考资料

本文作者: jsweibo

本文链接: https://jsweibo.github.io/2020/03/28/CSS%E4%B8%AD%E7%9A%84sticky%E5%AE%9A%E4%BD%8D/

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