SOURCE

window.onload= function() {
    Particles.init({
        selector: '.background',
        color: '#ffffff',
        maxParticles: 80,
        minDistance: 100,
        connectParticles: true,
    });

    const dot = document.getElementById('update-info-dot');
    let tickClock = 0;
    setInterval(() => {
        dot.innerHTML += '.'
        tickClock++
        if (tickClock > 3) {
            tickClock = 0;
            dot.innerHTML = ''
        }
    }, 800)
};

<div class="update-warpper">
    <div class="logo"></div>
    <canvas class="background" width="841" height="848" style="width: 100%; height: 100%;"></canvas>
    <div class="update-info-wrapper">
        <div class="update-info-main-text">
            网站正在升级中
            <span id="update-info-dot"></span>
        </div>
        <div class="update-info-text">
            更多功能即将呈现
        </div>
    </div>
    <div class="more-btn">
</div>

<script src="https://cdnjs.cloudflare.com/ajax/libs/particlesjs/2.2.2/particles.min.js"></script>

html,
body {
    width: 100%;
    height: 100%;
}

html,
body,
p,
ul,
li {
    margin: 0;
    border: 0;
    padding: 0;
}

.logo {
    position: absolute;
    top: 0px;
    right: 10px;
    background: url(https://quntuicdn.liankaa.com/corporation/img/liankaa_crm_logo.448a4b7.png) center no-repeat;
    width: 100px;
    height: 64px;
    background-size: contain;
}

.background {
    position: absolute;
    display: block;
    top: 0;
    left: 0;
    z-index: 0;
}

.update-warpper {
    width: 100%;
    height: 100%;
    text-align: center;
    padding-top: 150px;
    box-sizing: border-box;
    color: #ffffff;
    font-family: "SF Pro SC","SF Pro Text","SF Pro Icons","PingFang SC","Helvetica Neue","Helvetica","Arial",sans-serif;
    background: rgb(10,2,143);
    background: linear-gradient(53deg, rgba(10,2,143,1) 0%, rgba(67,67,171,1) 40%, rgba(82,82,207,1) 59%, rgba(0,212,255,1) 100%);
}

.update-info-main-text {
    font-size: 64px;
    margin-bottom: 50px;
    position: relative;
}

#update-info-dot {
    position: absolute;
    bottom: -10px;
    margin-left: 10px;
}

/* .update-info-main-text::after {
    content: "...";
    position: absolute;
    bottom: -10px;
    margin-left: 10px;
} */

.update-info-text {
    font-size: 32px;
}

.more-btn {
    margin: 0 auto;
    width: 50px;
    height: 5px;
    border-radius: 50px;
    background-color: #ffffff;
    position: absolute;
    bottom: 20px;
    left: 50%;
    margin-left: -25px;
    opacity: 1;
    animation: twinkle 3s infinite alternate;
}