90 lines
2.8 KiB
Markdown
90 lines
2.8 KiB
Markdown
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---
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id: 587d78a8367417b2b2512ae7
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title: Change Animation Timing with Keywords
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challengeType: 0
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videoUrl: ''
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localeTitle: 使用关键字更改动画计时
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---
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## Description
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<section id="description">在CSS动画中， <code>animation-timing-function</code>属性控制动画元素在动画持续时间内的变化速度。如果动画是在给定时间（ <code>animation-duration</code> ）从A点移动到B点的汽车，则<code>animation-timing-function</code>表示汽车在行驶过程中如何加速和减速。有许多预定义的关键字可用于热门选项。例如，默认值为<code>ease</code> ，它开始缓慢，在中间加速，然后在最后再次减速。其他选项包括<code>ease-out</code> ，在开始时快速然后减速， <code>ease-in</code> ，在开始时缓慢，然后在结束时加速，或<code>linear</code> ，其在整个过程中应用恒定的动画速度。 </section>
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## Instructions
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<section id="instructions">用于与ID的元素<code>ball1</code>和<code>ball2</code> ，一个添加<code>animation-timing-function</code>属性的每个，并设置<code>#ball1</code>至<code>linear</code> ，和<code>#ball2</code>到<code>ease-out</code> 。注意元素在动画期间如何移动但在一起结束之间的区别，因为它们共享相同的<code>animation-duration</code> 2秒。 </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: 具有id <code>ball1</code>的元素的<code>animation-timing-function</code>属性的值应该是线性的。
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testString: 'assert($("#ball1").css("animation-timing-function") == "linear", "The value of the <code>animation-timing-function</code> property for the element with the id <code>ball1</code> should be linear.");'
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- text: 具有id <code>ball2</code>的元素的<code>animation-timing-function</code>属性的<code>ball2</code>应该是缓出的。
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testString: 'assert($("#ball2").css("animation-timing-function") == "ease-out", "The value of the <code>animation-timing-function</code> property for the element with the id <code>ball2</code> should be ease-out.");'
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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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.balls {
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border-radius: 50%;
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background: linear-gradient(
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35deg,
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#ccffff,
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#ffcccc
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);
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position: fixed;
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width: 50px;
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height: 50px;
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margin-top: 50px;
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animation-name: bounce;
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animation-duration: 2s;
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animation-iteration-count: infinite;
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}
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#ball1 {
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left:27%;
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}
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#ball2 {
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left:56%;
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}
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@keyframes bounce {
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0% {
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top: 0px;
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}
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100% {
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top: 249px;
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}
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}
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</style>
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<div class="balls" id="ball1"></div>
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<div class="balls" id="ball2"></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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```js
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// solution required
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```
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</section>
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