上周六，产品经理钉钉发我一个腾讯公众号的链接，说：“你知道这是怎么实现的吗？”

经理说：“去搞下SVG，以后可以用这个写动画，这样的话，就不用 JS、CSS这么麻烦了。”

当我去了解并看手册学习过后，我内心更加充满疑问。SVG的优点是图像不会失帧不会不清晰，它的清晰度适合任何屏幕分辨率；比起gif、jpeg、png文件要小很多 ；但缺点是：不是所有的浏览器都支持，即老版的浏览器，老版的手机是不支持的。SVG有点像我上学那会玩的CAD，用坐标点画图。这图一点一点画出来？不可能，这怎么可能一个坐标点一个坐标点描绘出来，只为了一个图片点击变亮的动画？？

然后我回去打开链接，F12 打开一看，原来是用了2张图片，一张暗的，一张明亮的图片。当点击时，用animate把暗的图片opacity掉，这时肉眼就只看到明亮的图片。这时，我想吐血，为啥我不一开始就F12，😔。

<section style="height: 0px;">
        <svg data-copyright="GL" style="display: inline-block;width: 100%;vertical-align: top;background-position: 0% 0%;background-repeat: no-repeat;background-size:100% 100%;background-attachment: scroll;background-image: url(6402.png);-webkit-tap-highlight-color:transparent;-webkit-user-select:none;" viewBox="0 0 1080 720"></svg>
</section>
<svg data-copyright="GL" style="transform: scale(1);display: inline-block;width: 100%;vertical-align: top;background-size: 100% 100%;background-attachment: scroll;background-image: url(640.png);background-position: 0% 0%;background-repeat: no-repeat no-repeat;" viewBox="0 0 1080 720">
    <animate attributeName="opacity" begin="click" dur="3000s" keyTimes="0;0.001;1" values="1;0;0" fill="freeze" restart="whenNotActive"></animate>
</svg>
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我想换一种思路实现这个点击图片变亮，用最开始想的filter的grayscale(%)，再加个transition过度

先附上效果图

//css
.imgN{
    width: 300px;
    filter: grayscale(100%);
}
.imgactive{
    transition: all 1s ease-in-out;
    filter: grayscale(0);
}

//html
<div class="img" ><img class="imgN" src="6402.png" alt=""></div>
<script>
    document.querySelector('.imgN').addEventListener('click',function(){
        document.querySelector('.imgN').classList.toggle('imgactive')
    })
</script>
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不用点击，改用hover就更简单了。

//css就搞定了
.fourimg img{
    width: 300px;
    filter: grayscale(100%);
    transition: all 1s ease-in-out;
}
.fourimg img:hover{
   
    filter: grayscale(0);
}
//html
<div class="fourimg">
    <img src="6402.png" alt="">
</div>
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既然知道了SVG,不来点实际性的实操学习，不靠谱，不踏心。然后我就去了哔哩哔哩找了个视频教程跟着实操下，来附上哔哩哔哩作者的链接www.bilibili.com/video/BV1fJ…。

使用SVG实现丝滑流畅的上传按钮动画

老规矩，先附上效果图

这个思路是，先html用svg画出圆形、打勾、箭头、竖线以及虚线，接着css写样式以及动画，最后用js切换uploaded和uploading两个类，以及控制上传进度条。附上最终代码：

//html
<main>
    <div class="upload-button uploaded">
        <svg class="arrow" width='40' height='40' viewBox='0 0 40 40'>
            <circle cx='50%' cy='50%' r='19' fill='none' stroke='#fff' stroke-width='2'></circle>
            <polyline class="arrow-top" points='6,20 20,6 34,20' fill='none' stroke='#fff' stroke-width='2'></polyline>
            <line class="middle-line" x1='50%' y1='7' x2='50%' y2='34' stroke='#fff' stroke-width='2'></line>
            <polyline class="checkmark" points='8,20 18,30 30,12' fill='none' stroke='#fff' stroke-width='2'></polyline>
        </svg>
        <div class="progress-bar"></div>
    </div>
</main>

//css
*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "PingFang SC","Microsoft Yahei","sans-serif";
}
main{
    display: flex;
    align-items: center;
    justify-content: center;
    background: #222f3e;
    height: 100vh;
}
.upload-button{
    width: 180px;
    height: 60px;
    background-image: linear-gradient(160deg,#0093e9,#80d0c7);
    border-radius: 8px;
    cursor: pointer;
    box-shadow: 0 2px 10px rgb(0,147,233,0.28);

    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}
.upload-button .checkmark{
    opacity: 0;
}
.upload-button .progress-bar{
    position: absolute;
    /* width: 50%; */
    height: 2px;
    background-image: linear-gradient(45deg,#85ffbd,#fffb7d);
    bottom: 0;
    left: 0;
    border-radius: 4px;
}
.upload-button.uploading .middle-line{
    stroke-dasharray: 4 3;
    animation: 0.8s linear dashloop infinite;
}
.upload-button.uploading circle{
    animation: 1.5s linear blink infinite;
}

.upload-button.uploaded .arrow-top{
    animation: 1s linear arrowTransform forwards;
}

.upload-button.uploaded .checkmark{
    opacity: 1;
    stroke-dasharray: 100 100;
    stroke-dashoffset: 100;
    animation: 1s linear checkmarkTransform forwards 0.5s;
}

.upload-button.uploaded .middle-line{
    transform: 0.3s linear;
    opacity: 0;
}

@keyframes dashloop{
    from{
        stroke-dashoffset: 0;
    }
    to{
        stroke-dashoffset: 7;
    }
}
@keyframes blink{
    from{
        opacity: 1;
    }
    50%{
        opacity: 0.5;
    }
    to{
        opacity: 1;
    }
}

@keyframes arrowTransform{
    from{
        stroke-dasharray: 100 100;
        stroke-dashoffset: 0;
    }
    to{
        stroke-dasharray: 100 100;
        stroke-dashoffset: -100;
    }
}
@keyframes checkmarkTransform{
    from{
        stroke-dasharray: 100 100;
        stroke-dashoffset: 100;
    }
    to{
        stroke-dasharray: 100 100;
        stroke-dashoffset: 0;
    }
}

//js
var uploadButton = document.querySelector('.upload-button');
var progressBar = document.querySelector('.upload-button .progress-bar');

let width = uploadButton.getBoundingClientRect().width;
let uploadTime=5000;

uploadButton.addEventListener('click',function(){
    uploadButton.classList.remove('uploaded');
    uploadButton.classList.add('uploading');

    setTimeout(function(){
        uploadButton.classList.replace('uploading','uploaded');
    },uploadTime);

    //进度条
    let star = null;
    // timestamp 动画开始的时间戳
    function grow(timestamp){
        if(!star) star = timestamp;

        let progress = timestamp - star; //距离开始时过去了多少毫秒作为进度

        //根据 progress 按比例算出 该增加多少宽度 给进度条
        // Math.min 如果 宽度超出 按钮的宽度，就直接等于 按钮的宽度
        // width * (progress / uploadTime) 过去的毫秒 比上 总的毫秒  再 乘以 按钮宽度 就能算出 当前进度条时多少宽度
        progressBar.style.width=`${Math.min(width * (progress / uploadTime),width)}px`;


        //如果进度还没有到达 uploadTime ，则继续调用 requestAnimationFrame ，直到大于等于 uploadTime
        if(progress < uploadTime){
            window.requestAnimationFrame(grow);
        }
    }

    window.requestAnimationFrame(grow);
})
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嗯，我想旺哥（产品经理）的想法是：用svg做动画。但一整个下来，我也没觉得svg的动画比js,css简易多，是不是我想的太多，哈哈哈😄，肯定是我懒，不想去搞svg了。在工作中，我总是容易跑偏旺哥的想法，不知道我这次有没有跑偏，我也不敢问，也不敢说。如果你看到这篇文章，旺哥，在下方留言哈。😄