156 lines
3.1 KiB
Markdown
156 lines
3.1 KiB
Markdown
---
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id: 587d78a8367417b2b2512ae6
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title: 以可變速率來給多個元素添加動畫
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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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dashedName: animate-multiple-elements-at-variable-rates
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---
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# --description--
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在前面的關卡里，我們通過修改 `@keyframes` 改變了兩個相似動畫元素的頻率。 你也可以通過改變多個元素的 `animation-duration` 來達到同樣的效果。
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在代碼編輯器裏運行的動畫中，天空中有三顆以同樣頻率不停閃爍的星星。 你可以設置每一個星星的 `animation-duration` 屬性爲不同的值，以使其具有不同的閃爍頻率。
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# --instructions--
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依次設置 class 爲 `star-1`、`star-2`、`star-3` 的元素的 `animation-duration` 爲 1s、0.9s、1.1s。
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# --hints--
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class 爲 `star-1` 的 `animation-duration` 屬性值應該 1s。
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```js
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assert($('.star-1').css('animation-duration') == '1s');
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```
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class 爲 `star-2` 的 `animation-duration` 屬性值應該 0.9s。
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```js
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assert($('.star-2').css('animation-duration') == '0.9s');
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```
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class 爲 `star-3` 的 `animation-duration` 屬性值應該 1.1s。
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```js
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assert($('.star-3').css('animation-duration') == '1.1s');
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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-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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# --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-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: 0.9s;
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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: 1.1s;
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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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