效果预览按下右侧的“点击预览”按钮可以在当前页面预览，点击链接可以全屏预览。https://codepen.io/comehope/pen/rvgLzK可交互视频教程此视频是可以交互的，你可以随时暂停视频，编辑视频中的代码。请用 chrome, safari, edge 打开观看。https://scrimba.com/p/pEgDAM/cW7gZfb源代码下载每日前端实战系列的全部源代码请从 github 下载：https://github.com/comehope/front-end-daily-challenges代码解读定义 dom，容器中包含左拍、小球和右拍：<div class="court"> <div class="left-paddle"></div> <div class="ball"></div> <div class="right-paddle"></div></div>居中显示：body { height: 100vh; display: flex; align-items: center; justify-content: center; background: linear-gradient(silver, dimgray);}调整盒模型：* { box-sizing: border-box;}画出球案：.court { width: 20em; height: 20em; color: white; border: 1em solid currentColor;}画出左拍：.court { position: relative;}.left-paddle width: 1em; height: calc(50% - 1em); background-color: currentColor; position: absolute; top: 1em; left: 1em;}让左拍动起来：.left-paddle { animation: left-moving 1s linear infinite alternate;}@keyframes left-moving { to { transform: translateY(100%); }}类似地，画出右拍：.right-paddle width: 1em; height: calc(50% - 1em); background-color: currentColor; position: absolute; top: 1em; left: 1em; bottom: 1em; right: 1em;}类似地，让右拍动起来：.right-paddle { animation: right-moving 1s linear infinite alternate;}@keyframes right-moving { to { transform: translateY(-100%); }}画出小球：.ball { width: 100%; height: 1em; border-left: 1em solid currentColor; position: absolute; left: 2em; top: calc(50% - 1.5em);}让小球动起来：.ball { animation: bounce 1s linear infinite alternate;}@keyframes bounce { to { left: calc(100% - 3em); }}最后，重构一下左右拍的代码，合并共有属性：.left-paddle,.right-paddle { width: 1em; height: calc(50% - 1em); background-color: currentColor; position: absolute; animation: 1s linear infinite alternate;}.left-paddle { top: 1em; left: 1em; animation-name: left-moving;}.right-paddle { bottom: 1em; right: 1em; animation-name: right-moving;}大功告成！
