动画正在降低网页的性能

Question

我在 html、javascript 和 css 中有一个单页网站设计。网页上有很多图片，根据类别都有不同的动画效果。我已经使用 wow.js 在 window 滚动上实现动画效果。在滚动图像时，CPU 和 GPU 使用率非常高，由于其效果，滚动不流畅。任何人都可以看看这个。我创建了一个代码笔示例。请看:-

(https://codepen.io/Sny220/pen/jjyEPj)

代码如下：-



<!-- HTML -->
<div class="foo foo-text foo-2 col-md-3 col-md-offset-3 over-hidden">
   <img class="wow zoominoutsingle" src="https://www.psychologies.co.uk/sites/default/files/field/image/feelgood%20chemicals.jpg" />
</div>
<div class="foo foo-text foo-2 col-md-3 over-hidden">
   <img class="wow zoominoutsingle" src="https://kajabi-storefronts-production.global.ssl.fastly.net/kajabi-storefronts-production/blogs/1049/images/BlH7rBrRFGdVF71lofox_TFmaDj07ReWp5C4zcHaw_alex-fergus-look-and-feel-amazing-health-wellness-fat-loss-natural-banner.jpg" />
</div>
<div class="foo foo-text foo-2 col-md-6 col-md-offset-3">
   <div class="inner">
      <h1 class="wow fadeInDown">Hello, world!</h1>
      <p class="wow fadeInUp">Whouaa !!!</p>
   </div>
</div>
<div class="foo foo-3 col-md-6 col-md-offset-3">
   <div class="inner">
      <button type="button" class="btn btn-success">Success</button>
   </div>
</div>
<div class="foo foo-4 col-md-6 col-md-offset-3 wow fadeInDown">
   <img class="" src="http://www.ponpokopon.net/livresillu/unenouvellemaison1.jpg" />
</div>
<div class="foo foo-5 col-md-6 col-md-offset-3">
   <div class="inner">RUBRIQUE 3</div>
</div>
<div data-wow-duration="2s" class="foo foo-1 col-md-3 col-md-offset-3 wow scale-in-ver-top">
   <div class="inner">
      <img class="" src="http://www.ponpokopon.net/livresillu/unenouvellemaison2.jpg" />
   </div>
</div>
<div data-wow-duration="2s" class="foo  foo-2 col-md-3 wow scale-in-ver-top">
   <div class="inner"><img class="" src="https://media.treehugger.com/assets/images/2018/07/nature-benefits.jpg.860x0_q70_crop-scale.jpg" /></div>
</div>
<div data-wow-duration="2s" class="col-md-3 col-md-offset-3 margin-top-20 swing">
   <div class="inner"><img class="wow swing-in-top-fwd" src="https://www.thewaltdisneycompany.com/wp-content/uploads/ENVIRONMENT_header-option_Disney_Conservation_Fund_0348HC.jpg" /></div>
</div>
<div class="col-md-6 col-md-offset-3 bg-color">
   <h1 class="wow fadeInDown">Next Section</h1>
</div>
<!-- HTML -->
<div class="foo foo-text foo-2 col-md-3 col-md-offset-3 over-hidden">
   <img class="wow zoominoutsingle" src="https://www.psychologies.co.uk/sites/default/files/field/image/feelgood%20chemicals.jpg" />
</div>
<div class="foo foo-text foo-2 col-md-3 over-hidden">
   <img class="wow zoominoutsingle" src="https://kajabi-storefronts-production.global.ssl.fastly.net/kajabi-storefronts-production/blogs/1049/images/BlH7rBrRFGdVF71lofox_TFmaDj07ReWp5C4zcHaw_alex-fergus-look-and-feel-amazing-health-wellness-fat-loss-natural-banner.jpg" />
</div>
<div class="foo foo-text foo-2 col-md-6 col-md-offset-3">
   <div class="inner">
      <h1 class="wow fadeInDown">Hello, world!</h1>
      <p class="wow fadeInUp">Whouaa !!!</p>
   </div>
</div>
<div class="foo foo-3 col-md-6 col-md-offset-3">
   <div class="inner">
      <button type="button" class="btn btn-success">Success</button>
   </div>
</div>
<div class="foo foo-4 col-md-6 col-md-offset-3 wow fadeInDown">
   <img class="" src="http://www.ponpokopon.net/livresillu/unenouvellemaison1.jpg" />
</div>
<div class="foo foo-5 col-md-6 col-md-offset-3">
   <div class="inner">RUBRIQUE 3</div>
</div>
<div data-wow-duration="2s" class="foo foo-1 col-md-3 col-md-offset-3 wow scale-in-ver-top">
   <div class="inner">
      <img class="" src="http://www.ponpokopon.net/livresillu/unenouvellemaison2.jpg" />
   </div>
</div>
<div data-wow-duration="2s" class="foo  foo-2 col-md-3 wow scale-in-ver-top">
   <div class="inner"><img class="" src="https://media.treehugger.com/assets/images/2018/07/nature-benefits.jpg.860x0_q70_crop-scale.jpg" /></div>
</div>
<div data-wow-duration="2s" class="col-md-3 col-md-offset-3 margin-top-20 swing">
   <div class="inner"><img class="wow swing-in-top-fwd" src="https://www.thewaltdisneycompany.com/wp-content/uploads/ENVIRONMENT_header-option_Disney_Conservation_Fund_0348HC.jpg" /></div>
</div>
<div class="col-md-6 col-md-offset-3 bg-color">
   <h1 class="wow fadeInDown">Next Section</h1>
</div>
<!-- HTML -->
<div class="foo foo-text foo-2 col-md-3 col-md-offset-3 over-hidden">
   <img class="wow zoominoutsingle" src="https://www.psychologies.co.uk/sites/default/files/field/image/feelgood%20chemicals.jpg" />
</div>
<div class="foo foo-text foo-2 col-md-3 over-hidden">
   <img class="wow zoominoutsingle" src="https://kajabi-storefronts-production.global.ssl.fastly.net/kajabi-storefronts-production/blogs/1049/images/BlH7rBrRFGdVF71lofox_TFmaDj07ReWp5C4zcHaw_alex-fergus-look-and-feel-amazing-health-wellness-fat-loss-natural-banner.jpg" />
</div>
<div class="foo foo-text foo-2 col-md-6 col-md-offset-3">
   <div class="inner">
      <h1 class="wow fadeInDown">Hello, world!</h1>
      <p class="wow fadeInUp">Whouaa !!!</p>
   </div>
</div>
<div class="foo foo-3 col-md-6 col-md-offset-3">
   <div class="inner">
      <button type="button" class="btn btn-success">Success</button>
   </div>
</div>
<div class="foo foo-4 col-md-6 col-md-offset-3 wow fadeInDown">
   <img class="" src="http://www.ponpokopon.net/livresillu/unenouvellemaison1.jpg" />
</div>
<div class="foo foo-5 col-md-6 col-md-offset-3">
   <div class="inner">RUBRIQUE 3</div>
</div>
<div data-wow-duration="2s" class="foo foo-1 col-md-3 col-md-offset-3 wow scale-in-ver-top">
   <div class="inner">
      <img class="" src="http://www.ponpokopon.net/livresillu/unenouvellemaison2.jpg" />
   </div>
</div>
<div data-wow-duration="2s" class="foo  foo-2 col-md-3 wow scale-in-ver-top">
   <div class="inner"><img class="" src="https://media.treehugger.com/assets/images/2018/07/nature-benefits.jpg.860x0_q70_crop-scale.jpg" /></div>
</div>
<div data-wow-duration="2s" class="col-md-3 col-md-offset-3 margin-top-20 swing">
   <div class="inner"><img class="wow swing-in-top-fwd" src="https://www.thewaltdisneycompany.com/wp-content/uploads/ENVIRONMENT_header-option_Disney_Conservation_Fund_0348HC.jpg" /></div>
</div>
<div class="col-md-6 col-md-offset-3 bg-color">
   <h1 class="wow fadeInDown">Next Section</h1>
</div>
<!-- HTML -->
<div class="foo foo-text foo-2 col-md-3 col-md-offset-3">
   <img class="wow scale-in-ver-top" src="https://www.psychologies.co.uk/sites/default/files/field/image/feelgood%20chemicals.jpg" />
</div>
<div class="foo foo-text foo-2 col-md-3">
   <img class="wow scale-in-ver-top" src="https://kajabi-storefronts-production.global.ssl.fastly.net/kajabi-storefronts-production/blogs/1049/images/BlH7rBrRFGdVF71lofox_TFmaDj07ReWp5C4zcHaw_alex-fergus-look-and-feel-amazing-health-wellness-fat-loss-natural-banner.jpg" />
</div>
<div class="foo foo-text foo-2 col-md-6 col-md-offset-3">
   <div class="inner">
      <h1 class="wow fadeInDown">Hello, world!</h1>
      <p class="wow fadeInUp">Whouaa !!!</p>
   </div>
</div>
<div class="foo foo-3 col-md-6 col-md-offset-3">
   <div class="inner">
      <button type="button" class="btn btn-success">Success</button>
   </div>
</div>
<div class="foo foo-4 col-md-6 col-md-offset-3 wow fadeInDown">
   <img class="" src="http://www.ponpokopon.net/livresillu/unenouvellemaison1.jpg" />
</div>
<div class="foo foo-5 col-md-6 col-md-offset-3">
   <div class="inner">RUBRIQUE 3</div>
</div>
<div data-wow-duration="2s" class="foo foo-1 col-md-3 col-md-offset-3 wow scale-in-ver-top">
   <div class="inner">
      <img class="" src="http://www.ponpokopon.net/livresillu/unenouvellemaison2.jpg" />
   </div>
</div>
<div data-wow-duration="2s" class="foo  foo-2 col-md-3 wow scale-in-ver-top">
   <div class="inner"><img class="" src="https://media.treehugger.com/assets/images/2018/07/nature-benefits.jpg.860x0_q70_crop-scale.jpg" /></div>
</div>
<div data-wow-duration="2s" class="col-md-3 col-md-offset-3 margin-top-20 swing">
   <div class="inner"><img class="wow swing-in-top-fwd" src="https://www.thewaltdisneycompany.com/wp-content/uploads/ENVIRONMENT_header-option_Disney_Conservation_Fund_0348HC.jpg" /></div>
</div>
<div class="col-md-6 col-md-offset-3 bg-color">
   <h1 class="wow fadeInDown">Next Section</h1>
</div>
<!-- HTML -->
<div class="foo foo-text foo-2 col-md-3 col-md-offset-3">
   <img class="wow scale-in-ver-top" src="https://www.psychologies.co.uk/sites/default/files/field/image/feelgood%20chemicals.jpg" />
</div>
<div class="foo foo-text foo-2 col-md-3">
   <img class="wow scale-in-ver-top" src="https://kajabi-storefronts-production.global.ssl.fastly.net/kajabi-storefronts-production/blogs/1049/images/BlH7rBrRFGdVF71lofox_TFmaDj07ReWp5C4zcHaw_alex-fergus-look-and-feel-amazing-health-wellness-fat-loss-natural-banner.jpg" />
</div>
<div class="foo foo-text foo-2 col-md-6 col-md-offset-3">
   <div class="inner">
      <h1 class="wow fadeInDown">Hello, world!</h1>
      <p class="wow fadeInUp">Whouaa !!!</p>
   </div>
</div>
<div class="foo foo-3 col-md-6 col-md-offset-3">
   <div class="inner">
      <button type="button" class="btn btn-success">Success</button>
   </div>
</div>
<div class="foo foo-4 col-md-6 col-md-offset-3 wow fadeInDown">
   <img class="" src="http://www.ponpokopon.net/livresillu/unenouvellemaison1.jpg" />
</div>
<div class="foo foo-5 col-md-6 col-md-offset-3">
   <div class="inner">RUBRIQUE 3</div>
</div>
<div data-wow-duration="2s" class="foo foo-1 col-md-3 col-md-offset-3 wow scale-in-ver-top">
   <div class="inner">
      <img class="" src="http://www.ponpokopon.net/livresillu/unenouvellemaison2.jpg" />
   </div>
</div>
<div data-wow-duration="2s" class="foo  foo-2 col-md-3 wow scale-in-ver-top">
   <div class="inner"><img class="" src="https://media.treehugger.com/assets/images/2018/07/nature-benefits.jpg.860x0_q70_crop-scale.jpg" /></div>
</div>
<div data-wow-duration="2s" class="col-md-3 col-md-offset-3 margin-top-20 swing">
   <div class="inner"><img class="wow swing-in-top-fwd" src="https://www.thewaltdisneycompany.com/wp-content/uploads/ENVIRONMENT_header-option_Disney_Conservation_Fund_0348HC.jpg" /></div>
</div>



body {
    padding-top: 20px;
}


/* set colors*/

 :root {
    --color-1: forestgreen;
    --color-2: lightskyblue;
    --color-3: darksalmon;
    --color-4: palegoldenrod;
    --color-5: mediumvioletred;
}

img {
    width: 100%;
}

.foo {
    margin-bottom: 10px;
    color: white;
}

.navbar {}

.foo .inner {
    padding: 5px;
    min-height: 20vh;
}

.foo-text .inner {
    min-height: 60vh !important;
}


/* apply colors */

.foo-1 .inner {
    background-color: var(--color-1);
}

.foo-2 .inner {
    background-color: var(--color-2);
}

.foo-3 .inner {
    background-color: var(--color-3);
}

.foo-4 .inner {
    background-color: var(--color-4);
}

.foo-5 .inner {
    background-color: var(--color-5);
}

.bg-color {
    background-color: var(--color-5);
    color: #fff;
    margin-top: 20px;
    margin-bottom: 20px;
}

.over-hidden {
    overflow: hidden;
}

.swing {
    overflow: hidden;
}

.scale-in-ver-top {
    -webkit-animation: scale-in-ver-top 0.5s cubic-bezier(0.250, 0.460, 0.450, 0.940) both;
    animation: scale-in-ver-top 0.5s cubic-bezier(0.250, 0.460, 0.450, 0.940) both;
}

@-webkit-keyframes scale-in-ver-top {
    0% {
        -webkit-transform: scaleY(0);
        transform: scaleY(0);
        -webkit-transform-origin: 100% 0%;
        transform-origin: 100% 0%;
        opacity: 1;
    }
    100% {
        -webkit-transform: scaleY(1);
        transform: scaleY(1);
        -webkit-transform-origin: 100% 0%;
        transform-origin: 100% 0%;
        opacity: 1;
    }
}

@keyframes scale-in-ver-top {
    0% {
        -webkit-transform: scaleY(0);
        transform: scaleY(0);
        -webkit-transform-origin: 100% 0%;
        transform-origin: 100% 0%;
        opacity: 1;
    }
    100% {
        -webkit-transform: scaleY(1);
        transform: scaleY(1);
        -webkit-transform-origin: 100% 0%;
        transform-origin: 100% 0%;
        opacity: 1;
    }
}

.swing-in-top-fwd {
    -webkit-animation-name: swing-in-top-fwd;
    animation-name: swing-in-top-fwd;
}

@-webkit-keyframes swing-in-top-fwd {
    0% {
        -webkit-transform: rotateX(-100deg);
        transform: rotateX(-100deg);
        -webkit-transform-origin: top;
        transform-origin: top;
        opacity: 0;
        -webkit-animation-timing-function: cubic-bezier(0.175, 0.885, 0.320, 1.275);
        animation-timing-function: cubic-bezier(0.175, 0.885, 0.320, 1.275);
    }
    100% {
        -webkit-transform: rotateX(0deg);
        transform: rotateX(0deg);
        -webkit-transform-origin: top;
        transform-origin: top;
        opacity: 1;
        -webkit-animation-timing-function: cubic-bezier(0.175, 0.885, 0.320, 1.275);
        animation-timing-function: cubic-bezier(0.175, 0.885, 0.320, 1.275);
    }
}

@keyframes swing-in-top-fwd {
    0% {
        -webkit-transform: rotateX(-100deg);
        transform: rotateX(-100deg);
        -webkit-transform-origin: top;
        transform-origin: top;
        opacity: 0;
        -webkit-animation-timing-function: cubic-bezier(0.175, 0.885, 0.320, 1.275);
        animation-timing-function: cubic-bezier(0.175, 0.885, 0.320, 1.275);
    }
    100% {
        -webkit-transform: rotateX(0deg);
        transform: rotateX(0deg);
        -webkit-transform-origin: top;
        transform-origin: top;
        opacity: 1;
        -webkit-animation-timing-function: cubic-bezier(0.175, 0.885, 0.320, 1.275);
        animation-timing-function: cubic-bezier(0.175, 0.885, 0.320, 1.275);
    }
}

@keyframes zoominoutsinglefeatured {
    0% {
        transform: scale(1, 1);
        webkit-transform: scale(1, 1);
    }
    50% {
        transform: scale(2, 2);
        webkit-transform: scale(2, 2);
    }
    100% {
        transform: scale(1, 1);
        webkit-transform: scale(1, 1);
    }
}

.zoominoutsingle {
    animation-name: zoominoutsinglefeatured;
    webkit-animation-name: zoominoutsinglefeatured;
    -webkit-animation-duration: 10s;
    animation-duration: 10s;
    -webkit-animation-fill-mode: both;
    animation-fill-mode: both;
}

wow = new WOW();
wow.init();

$(".foo-5").hover(function(e) {
    $(this).addClass('animated pulse');
}, function(e) {
    $(this).removeClass('animated pulse');
});
var $animation_elements = $('.wow');
var $window = $(window);

function check_if_in_view() {
    var window_height = $window.height();
    var window_top_position = $window.scrollTop();
    var window_bottom_position = (window_top_position + window_height);

    $.each($animation_elements, function() {
        var $element = $(this);
        var element_height = $element.outerHeight();
        var element_top_position = $element.offset().top;
        var element_bottom_position = (element_top_position + element_height);

        //check to see if this current container is within viewport
        if ((element_bottom_position >= window_top_position) &&
            (element_top_position <= window_bottom_position)) {
            $element.removeClass('animated');
            $element.addClass('animated');
        } else {
            $element.css({
                'visibility': 'hidden',
                'animation-name': 'none'
            }).removeClass('animated');
            wow.addBox(this);
        }
    });
}
WOW.prototype.addBox = function(element) {
    this.boxes.push(element);
};
$window.on('scroll resize', check_if_in_view);

update:- This is just an example that i am using in webpage. Web page has different number of sections apporx. 20 sections and all are having 10 or more images. So when we are running that much images with animations the performance goes down.

I have checked it on mac Safari 11 & 12, the animation and scroll is not smooth. There is jerkiness while scrolling and animations are very slow with jerks.

Answer 1

通过使用 Intersection Observer (IO) 而不是侦听滚动事件，您可能会获得很多性能。引入IO是因为监听scroll事件，计算元素的height/width，导致性能不佳。

首先你必须创建一个新的观察者：

var options = {
  rootMargin: '0px',
  threshold: 1.0
 }

var observer = new IntersectionObserver(callback, options);

这里我们指定一旦观察到的元素 100% 可见，就应该执行一些回调。

然后你必须指定要观察的项目，在你的情况下我认为这将是：

var target = document.querySelector('.wow');
observer.observe(target);

所以我们定义一旦带有 class "wow" 的任何元素在页面上可见，回调就会被执行：

var callback = function(entries, observer) { 
  entries.forEach(entry => {
  // Each entry describes an intersection change for one observed
  // target element:
  });
};

您可以在此处指定页面中每个可见的 "wow" 元素应该发生什么。

如果您使用 CSS 制作动画而不是 JS，那么动画现在应该很流畅了。它还取决于您要设置动画的参数，这里 is a good list of properties 避免使用 CSS 设置动画。

我不会在这里复制整个列表，但最重要的是填充、宽度、高度和位置。

编辑：如果您需要支持比使用此（官方）polyfill from w3c 更旧的浏览器，它会通过侦听滚动事件重新创建路口观察器。所以它在旧浏览器上仍然会变慢，你在这里无能为力。但在较新的产品上，性能会有所提高。

Answer 2

您可以对动画使用延迟加载，并以更好的方式执行视图元素的加载。 JQuery Lazy

Answer 3

由于您似乎只使用了 animated pulse，并且已经在添加和删除 animated class，我强烈建议您使用 CSS 动画.

CSS 动画是用 GPU 渲染的，不像 JavaScript 那样使用主线程。它们超级流畅且性能卓越！

看看我在 Google 上找到的这个 Codepen，它创建了一个脉冲动画图标：https://codepen.io/igorsheg/pen/MBpwGw

动画正在降低网页的性能

Animations are slowing the performance of web page

javascript

jquery

cpu-usage

wow.js