142 lines
2.7 KiB
Markdown
142 lines
2.7 KiB
Markdown
---
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id: 587d78a8367417b2b2512ae5
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title: 以可变速率来给元素添加动画
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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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dashedName: animate-elements-at-variable-rates
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---
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# --description--
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改变相似元素的动画频率的方法有很多。 目前我们接触到的就有 `animation-iteration-count` 和 `@keyframes`。
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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 `@keyframes` 为 20% 处变小并且透明度变低，也就是一闪一闪的动画效果。 你可以通过改变其中一个元素的 `@keyframes` 规则以使两个小星星以不同的频率闪烁。
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# --instructions--
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请将 class 为 `star-1` 的元素的 `@keyframes` 为设置为 50%，以此改变其动画频率。
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# --hints--
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class 为 `star-1` 的元素的 `@keyframes` 规则应为 50%。
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```js
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assert(code.match(/twinkle-1\s*?{\s*?50%/g));
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```
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# --seed--
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## --seed-contents--
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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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# --solutions--
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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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50% {
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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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