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标签 javascript html css
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start 我为多步动画编写了以下代码。但我想得到如上图所示的结果。即,一旦网页启动,只会显示黑色垂直条。 stop .然后如屏幕截图所示,如果我在控制台运行 start() 它应该运行动画,如果我在控制台运行 stop() 它应该回到垂直条。
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<style>
$max: 100px;
.equilizer {
height: $max;
width: $max;
transform: rotate(180deg);
}
.bar {
fill: DeepPink;
width: 18px;
animation: equalize 1.25s steps(25, end) 0s infinite;
}
.bar:nth-child(1) {
animation-duration: 1.9s;
}
.bar:nth-child(2) {
animation-duration: 2s;
}
.bar:nth-child(3) {
animation-duration: 2.3s;
}
.bar:nth-child(4) {
animation-duration: 2.4s;
}
.bar:nth-child(5) {
animation-duration: 2.1s;
}
@keyframes equalize {
0% {
height: 60px;
}
4% {
height: 50px;
}
8% {
height: 40px;
}
12% {
height: 30px;
}
16% {
height: 20px;
}
20% {
height: 30px;
}
24% {
height: 40px;
}
28% {
height: 10px;
}
32% {
height: 40px;
}
36% {
height: 60px;
}
40% {
height: 20px;
}
44% {
height: 40px;
}
48% {
height: 70px;
}
52% {
height: 30px;
}
56% {
height: 10px;
}
60% {
height: 30px;
}
64% {
height: 50px;
}
68% {
height: 60px;
}
72% {
height: 70px;
}
76% {
height: 80px;
}
80% {
height: 70px;
}
84% {
height: 60px;
}
88% {
height: 50px;
}
92% {
height: 60px;
}
96% {
height: 70px;
}
100% {
height: 80px;
}
}
</style>
</head>
<body>
<svg xmlns="http://www.w3.org/2000/svg" class="equilizer" viewBox="0 0 128 128">
<g>
<title>Audio Equilizer</title>
<rect class="bar" transform="translate(0,0)" y="15"></rect>
<rect class="bar" transform="translate(25,0)" y="15"></rect>
<rect class="bar" transform="translate(50,0)" y="15"></rect>
<rect class="bar" transform="translate(75,0)" y="15"></rect>
<rect class="bar" transform="translate(100,0)" y="15"></rect>
</g>
</svg>
</body>
</html>
现在默认动画应该处于停止模式。我将如何使用简单的 JavaScript 进行此操作(建议我不要使用任何外部框架/库,除了简单的 HTML、CSS 和 JAVASCRIPT)。
最佳答案
在我看来,您可以通过在相关元素中添加或删除 bar
类来打开和关闭动画:
var bars = document.querySelectorAll('rect');
for (var i = 0; i < bars.length; i++)
bars[i].classList.toggle('bar');
将该代码放入一个函数中,您可以根据需要从控制台调用它,但出于演示目的(展开代码段以查看它的工作原理),我将其包含在按钮的点击处理程序中:
var bars = document.querySelectorAll('rect');
document.getElementById("startstop").addEventListener("click", function(e) {
this.innerHTML = this.innerHTML === "Start" ? "Stop" : "Start";
for (var i = 0; i < bars.length; i++)
bars[i].classList.toggle('bar');
});
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<style>
$max: 100px;
.equilizer {
height: $max;
width: $max;
transform: rotate(180deg);
}
.bar {
fill: DeepPink;
width: 18px;
animation: equalize 1.25s steps(25, end) 0s infinite;
}
.bar:nth-child(1) {
animation-duration: 1.9s;
}
.bar:nth-child(2) {
animation-duration: 2s;
}
.bar:nth-child(3) {
animation-duration: 2.3s;
}
.bar:nth-child(4) {
animation-duration: 2.4s;
}
.bar:nth-child(5) {
animation-duration: 2.1s;
}
@keyframes equalize {
0% {
height: 60px;
}
4% {
height: 50px;
}
8% {
height: 40px;
}
12% {
height: 30px;
}
16% {
height: 20px;
}
20% {
height: 30px;
}
24% {
height: 40px;
}
28% {
height: 10px;
}
32% {
height: 40px;
}
36% {
height: 60px;
}
40% {
height: 20px;
}
44% {
height: 40px;
}
48% {
height: 70px;
}
52% {
height: 30px;
}
56% {
height: 10px;
}
60% {
height: 30px;
}
64% {
height: 50px;
}
68% {
height: 60px;
}
72% {
height: 70px;
}
76% {
height: 80px;
}
80% {
height: 70px;
}
84% {
height: 60px;
}
88% {
height: 50px;
}
92% {
height: 60px;
}
96% {
height: 70px;
}
100% {
height: 80px;
}
}
</style>
</head>
<body>
<button id="startstop" type="button">Start</button>
<svg xmlns="http://www.w3.org/2000/svg" class="equilizer" viewBox="0 0 128 128">
<g>
<title>Audio Equilizer</title>
<rect transform="translate(0,0)" y="15"></rect>
<rect transform="translate(25,0)" y="15"></rect>
<rect transform="translate(50,0)" y="15"></rect>
<rect transform="translate(75,0)" y="15"></rect>
<rect transform="translate(100,0)" y="15"></rect>
</g>
</svg>
</body>
</html>
或者您可以稍微更改您的 CSS 以仅将动画应用于作为具有特定类的元素的子元素的 .bar
元素,然后从父元素中添加或删除该类:
var barParent = document.querySelector('g');
document.getElementById("startstop").addEventListener("click", function(e) {
this.innerHTML = this.innerHTML === "Start" ? "Stop" : "Start";
barParent.classList.toggle('barstarted');
});
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<style>
$max: 100px;
.equilizer {
height: $max;
width: $max;
transform: rotate(180deg);
}
.barstarted .bar { /* ---- note this change */
fill: DeepPink;
width: 18px;
animation: equalize 1.25s steps(25, end) 0s infinite;
}
.bar:nth-child(1) {
animation-duration: 1.9s;
}
.bar:nth-child(2) {
animation-duration: 2s;
}
.bar:nth-child(3) {
animation-duration: 2.3s;
}
.bar:nth-child(4) {
animation-duration: 2.4s;
}
.bar:nth-child(5) {
animation-duration: 2.1s;
}
@keyframes equalize {
0% {
height: 60px;
}
4% {
height: 50px;
}
8% {
height: 40px;
}
12% {
height: 30px;
}
16% {
height: 20px;
}
20% {
height: 30px;
}
24% {
height: 40px;
}
28% {
height: 10px;
}
32% {
height: 40px;
}
36% {
height: 60px;
}
40% {
height: 20px;
}
44% {
height: 40px;
}
48% {
height: 70px;
}
52% {
height: 30px;
}
56% {
height: 10px;
}
60% {
height: 30px;
}
64% {
height: 50px;
}
68% {
height: 60px;
}
72% {
height: 70px;
}
76% {
height: 80px;
}
80% {
height: 70px;
}
84% {
height: 60px;
}
88% {
height: 50px;
}
92% {
height: 60px;
}
96% {
height: 70px;
}
100% {
height: 80px;
}
}
</style>
</head>
<body>
<button id="startstop" type="button">Start</button>
<svg xmlns="http://www.w3.org/2000/svg" class="equilizer" viewBox="0 0 128 128">
<g>
<title>Audio Equilizer</title>
<rect class="bar" transform="translate(0,0)" y="15"></rect>
<rect class="bar" transform="translate(25,0)" y="15"></rect>
<rect class="bar" transform="translate(50,0)" y="15"></rect>
<rect class="bar" transform="translate(75,0)" y="15"></rect>
<rect class="bar" transform="translate(100,0)" y="15"></rect>
</g>
</svg>
</body>
</html>
关于javascript - 如何在使用 Javascript 在控制台中调用 start() 和 stop() 时启动和删除多步动画?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39684019/