111 lines
2.5 KiB
Markdown
111 lines
2.5 KiB
Markdown
---
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id: 587d78a8367417b2b2512ae6
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challengeType: 0
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videoUrl: 'https://scrimba.com/c/cnpWZc9'
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forumTopicId: 301042
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title: 以可变速率来给多个元素添加动画
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---
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## Description
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<section id='description'>
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在前面的关卡里，你通过改变 <code>@keyframes</code> 改变了两个相似动画元素的频率。你也可以通过改变多个元素的 <code>animation-duration</code> 来达到同样的效果。
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在编辑器代码运行的动画里，天空中有三个以同样频率不停的闪烁的星星。你可以设置每一个星星的 <code>animation-duration</code> 属性为不同的值来使其具有不同的闪烁频率。
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</section>
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## Instructions
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<section id='instructions'>
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依次设置 class 为 <code>star-1</code>、<code>star-2</code>、<code>star-3</code> 的 <code>animation-duration</code> 为 1s、0.9s、1.1s。
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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: 'class 为 <code>star-1</code> 的 <code>animation-duration</code> 属性值应该 1s。'
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testString: assert($('.star-1').css('animation-duration') == '1s');
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- text: 'class 为 <code>star-2</code> 的 <code>animation-duration</code> 属性值应该 0.9s。'
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testString: assert($('.star-2').css('animation-duration') == '0.9s');
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- text: 'class 为 <code>star-3</code> 的 <code>animation-duration</code> 属性值应该 1.1s。'
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testString: assert($('.star-3').css('animation-duration') == '1.1s');
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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-duration: 1s;
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animation-name: twinkle;
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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-duration: 1s;
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animation-name: twinkle;
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}
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.star-3 {
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margin-top: 10%;
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margin-left: 50%;
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animation-duration: 1s;
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animation-name: twinkle;
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}
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@keyframes twinkle {
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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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<div class="star-3 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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