108 lines
2.2 KiB
Markdown
108 lines
2.2 KiB
Markdown
---
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id: 587d78a8367417b2b2512ae5
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title: Animate Elements at Variable Rates
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challengeType: 0
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videoUrl: 'https://scrimba.com/c/cZ89WA4'
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forumTopicId: 301040
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localeTitle: 以可变速率来给元素添加动画
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---
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## Description
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<section id='description'>
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改变相似元素的动画频率的方法有很多。目前接触到的就有 <code>animation-iteration-count</code> 和 <code>@keyframes</code>。
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举例说明，右边的动画包含了两个小星星，每个小星星都在 20% <code>@keyframes</code> 处变小并且 opacity 变为 20%，也就是一闪一闪的动画效果。你可以通过改变其中一个星星的 <code>@keyframes</code> 规则以使两个小星星以不同的频率闪烁。
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</section>
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## Instructions
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<section id='instructions'>
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通过改变 class 为 <code>star-1</code> 的元素的 <code>@keyframes</code> 为 50% 以改变其动画频率。
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: '<code>star-1</code> class 的 <code>@keyframes</code> 规则应该为50%。'
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testString: assert(code.match(/twinkle-1\s*?{\s*?50%/g), '<code>star-1</code>class 的 <code>@keyframes</code> 规则应该为50%。');
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='html-seed'>
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```html
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<style>
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.stars {
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background-color: white;
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height: 30px;
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width: 30px;
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border-radius: 50%;
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animation-iteration-count: infinite;
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}
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.star-1 {
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margin-top: 15%;
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margin-left: 60%;
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animation-name: twinkle-1;
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animation-duration: 1s;
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}
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.star-2 {
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margin-top: 25%;
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margin-left: 25%;
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animation-name: twinkle-2;
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animation-duration: 1s;
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}
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@keyframes twinkle-1 {
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20% {
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transform: scale(0.5);
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opacity: 0.5;
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}
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}
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@keyframes twinkle-2 {
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20% {
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transform: scale(0.5);
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opacity: 0.5;
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}
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}
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#back {
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position: fixed;
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padding: 0;
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margin: 0;
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top: 0;
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left: 0;
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width: 100%;
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height: 100%;
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background: linear-gradient(black, #000099, #66c2ff, #ffcccc, #ffeee6);
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}
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</style>
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<div id="back"></div>
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<div class="star-1 stars"></div>
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<div class="star-2 stars"></div>
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```html
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// solution required
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```
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</section>
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