Create Animated Download button in CSS & jQuery

<div class="container">
 
    <a href="" class="button">
        <ul>
            <li>&#68;ownload</li>
            <li>&#68;ownloading</li>
            <li>Open File</li>
        </ul>
        <div>
            <svg viewBox="0 0 24 24"></svg>
        </div>
    </a>
 
    <a href="" class="button dark-single">
        <div>
            <svg viewBox="0 0 24 24"></svg>
        </div>
    </a>
 
    <div></div>
 
    <a href="" class="button white-single">
        <div>
            <svg viewBox="0 0 24 24"></svg>
        </div>
    </a>
 
    <a href="" class="button dark">
        <ul>
            <li>&#68;ownload</li>
            <li>&#68;ownloading</li>
            <li>Open File</li>
        </ul>
        <div>
            <svg viewBox="0 0 24 24"></svg>
        </div>
    </a>
 
</div>
 
<!-- dribbble -->
<a class="dribbble" href="https://dribbble.com/shots/7299868-Download-Buttons" target="_blank"><img src="https://cdn.dribbble.com/assets/dribbble-ball-mark-2bd45f09c2fb58dbbfb44766d5d1d07c5a12972d602ef8b32204d28fa3dda554.svg" alt=""></a>

.button {
    &.dark-single {
        --background: none;
        --rectangle: #242836;
        --success: #4BC793;
    }
    &.white-single {
        --background: none;
        --rectangle: #F5F9FF;
        --arrow: #275efe;
        --success: #275efe;
        --shadow: rgba(10, 22, 50, .1);
    }
    &.dark {
        --background: #242836;
        --rectangle: #1C212E;
        --arrow: #F5F9FF;
        --text: #F5F9FF;
        --success: #2F3545;
    }
}
 
.button {
    --background: #275efe;
    --rectangle: #184fee;
    --success: #{mix(white, #184fee, 20%)};
    --text: #fff;
    --arrow: #fff;
    --checkmark: #fff;
    --shadow: rgba(10, 22, 50, .24);
    display: flex;
    overflow: hidden;
    text-decoration: none;
    -webkit-mask-image: -webkit-radial-gradient(white, black);
    background: var(--background);
    border-radius: 8px;
    box-shadow: 0 2px 8px -1px var(--shadow);
    transition: transform .2s ease, box-shadow .2s ease;
    &:active {
        transform: scale(.95);
        box-shadow: 0 1px 4px -1px var(--shadow);
    }
    ul {
        margin: 0;
        padding: 16px 40px;
        list-style: none;
        text-align: center;
        position: relative;
        backface-visibility: hidden;
        font-size: 16px;
        font-weight: 500;
        line-height: 28px;
        color: var(--text);
        li {
            &:not(:first-child) {
                top: 16px;
                left: 0;
                right: 0;
                position: absolute;
            }
            &:nth-child(2) {
                top: 76px;
            }
            &:nth-child(3) {
                top: 136px;
            }
        }
    }
    & > div {
        position: relative;
        width: 60px;
        height: 60px;
        background: var(--rectangle);
        &:before,
        &:after {
            content: '';
            display: block;
            position: absolute;
        }
        &:before {
            border-radius: 1px;
            width: 2px;
            top: 50%;
            left: 50%;
            height: 17px;
            margin: -9px 0 0 -1px;
            background: var(--arrow);
        }
        &:after {
            width: 60px;
            height: 60px;
            transform-origin: 50% 0;
            border-radius: 0 0 80% 80%;
            background: var(--success);
            top: 0;
            left: 0;
            transform: scaleY(0);
        }
        svg {
            display: block;
            position: absolute;
            width: 20px;
            height: 20px;
            left: 50%;
            top: 50%;
            margin: -9px 0 0 -10px;
            fill: none;
            z-index: 1;
            stroke-width: 2px;
            stroke: var(--arrow);
            stroke-linecap: round;
            stroke-linejoin: round;
        }
    }
    &.loading {
        ul {
            animation: text calc(var(--duration) * 1ms) linear forwards calc(var(--duration) * .065ms);
        }
        & > div {
            &:before {
                animation: line calc(var(--duration) * 1ms) linear forwards calc(var(--duration) * .065ms);
            }
            &:after {
                animation: background calc(var(--duration) * 1ms) linear forwards calc(var(--duration) * .065ms);
            }
            svg {
                animation: svg calc(var(--duration) * 1ms) linear forwards calc(var(--duration) * .065ms);
            }
        }
    }
}
 
@keyframes text {
    10%,
    85% {
        transform: translateY(-100%);
    }
    95%,
    100% {
        transform: translateY(-200%);
    }
}
 
@keyframes line {
    5%,
    10% {
        transform: translateY(-30px);
    }
    40% {
        transform: translateY(-20px);
    }
    65% {
        transform: translateY(0);
    }
    75%,
    100% {
        transform: translateY(30px);
    }
}
 
@keyframes svg {
    0%,
    20% {
        stroke-dasharray: 0;
        stroke-dashoffset: 0;
    }
    21%,
    89% {
        stroke-dasharray: 26px;
        stroke-dashoffset: 26px;
        stroke-width: 3px;
        margin: -10px 0 0 -10px;
        stroke: var(--checkmark);
    }
    100% {
        stroke-dasharray: 26px;
        stroke-dashoffset: 0;
        margin: -10px 0 0 -10px;
        stroke: var(--checkmark);
    }
    12% {
        opacity: 1;
    }
    20%,
    89% {
        opacity: 0;
    }
    90%,
    100% {
        opacity: 1;
    }
}
 
@keyframes background {
    10% {
        transform: scaleY(0);
    }
    40% {
        transform: scaleY(.15);
    }
    65% {
        transform: scaleY(.5);
        border-radius: 0 0 50% 50%;
    }
    75% {
        border-radius: 0 0 50% 50%;
    }
    90%,
    100% {
        border-radius: 0;
    }
    75%,
    100% {
        transform: scaleY(1);
    }
}
 
html {
    box-sizing: border-box;
    -webkit-font-smoothing: antialiased;
}
 
* {
    box-sizing: inherit;
    &:before,
    &:after {
        box-sizing: inherit;
    }
}
 
// Center & dribbble
body {
    min-height: 100vh;
    display: flex;
    font-family: 'Roboto', Arial;
    justify-content: center;
    align-items: center;
    background: #E4ECFA;
    .container {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        & > div {
            flex-basis: 100%;
            width: 0;
        }
        .button {
            margin: 16px;
            @media(max-width: 400px) {
                margin: 12px;
            }
        }
    }
    .dribbble {
        position: fixed;
        display: block;
        right: 20px;
        bottom: 20px;
        img {
            display: block;
            height: 28px;
        }
    }
}

$('.button').each(function(e) {
 
    let duration = 3000,
        btn = $(this),
        svg = btn.find('svg'),
        svgPath = new Proxy({
            y: null,
            smoothing: null
        }, {
            set(target, key, value) {
                target[key] = value;
                if(target.y !== null && target.smoothing !== null) {
                    svg.html(getPath(target.y, target.smoothing, null))
                }
                return true;
            },
            get(target, key) {
                return target[key];
            }
        });
 
    btn.css('--duration', duration);
 
    svgPath.y = 20;
    svgPath.smoothing = 0;
 
    btn.on('click', e => {
 
        if(!btn.hasClass('loading')) {
 
            btn.addClass('loading');
 
            TweenMax.to(svgPath, duration * .065 / 1000, {
                smoothing: .3
            });
 
            TweenMax.to(svgPath, duration * .265 / 1000, {
                y: 12,
                ease: Elastic.easeOut.config(1.12, .4)
            }).delay(duration * .065 / 1000);
 
            setTimeout(() => {
                svg.html(getPath(0, 0, [
                    [3, 14],
                    [8, 19],
                    [21, 6]
                ]));
            }, (duration / 2));
 
        }
 
        return false;
 
    });
 
});
 
function getPoint(point, i, a, smoothing) {
    let cp = (current, previous, next, reverse) => {
            let p = previous || current,
                n = next || current,
                o = {
                    length: Math.sqrt(Math.pow(n[0] - p[0], 2) + Math.pow(n[1] - p[1], 2)),
                    angle: Math.atan2(n[1] - p[1], n[0] - p[0])
                },
                angle = o.angle + (reverse ? Math.PI : 0),
                length = o.length * smoothing;
            return [current[0] + Math.cos(angle) * length, current[1] + Math.sin(angle) * length];
        },
        cps = cp(a[i - 1], a[i - 2], point, false),
        cpe = cp(point, a[i - 1], a[i + 1], true);
    return `C ${cps[0]},${cps[1]} ${cpe[0]},${cpe[1]} ${point[0]},${point[1]}`;
}
 
function getPath(update, smoothing, pointsNew) {
    let points = pointsNew ? pointsNew : [
            [4, 12],
            [12, update],
            [20, 12]
        ],
        d = points.reduce((acc, point, i, a) => i === 0 ? `M ${point[0]},${point[1]}` : `${acc} ${getPoint(point, i, a, smoothing)}`, '');
    return `<path d="${d}" />`;
}