https://zhuanlan.zhihu.com/p/28257724
https://cloud.tencent.com/developer/article/1619012


![](https://pic1.zhimg.com/v2-c84e0527949ec8f63832ad757f18d3c9_1440w.jpg?source=172ae18b)

```html
<style>
    canvas {
      position: fixed;
      top: 0;
      left: 0;
      z-index: 0;
      width: 100%;
      height: 100%;
      pointer-events: none;
    }
</style>
<canvas></canvas>
<script>
    document.addEventListener('touchmove', function (e) {
        e.preventDefault()
    })
    var c = document.getElementsByTagName('canvas')[0],
        x = c.getContext('2d'),
        pr = window.devicePixelRatio || 1,
        w = window.innerWidth,
        h = window.innerHeight,
        f = 90,
        q,
        m = Math,
        r = 0,
        u = m.PI*2,
        v = m.cos,
        z = m.random
    c.width = w*pr
    c.height = h*pr
    x.scale(pr, pr)
    x.globalAlpha = 0.6
    function i(){
        x.clearRect(0,0,w,h)
        q=[{x:0,y:h*.7+f},{x:0,y:h*.7-f}]
        while(q[1].x<w+f) d(q[0], q[1])
    }
    function d(i,j){   
        x.beginPath()
        x.moveTo(i.x, i.y)
        x.lineTo(j.x, j.y)
        var k = j.x + (z()*2-0.25)*f,
            n = y(j.y)
        x.lineTo(k, n)
        x.closePath()
        r-=u/-50
        x.fillStyle = '#'+(v(r)*127+128<<16 | v(r+u/3)*127+128<<8 | v(r+u/3*2)*127+128).toString(16)
        x.fill()
        q[0] = q[1]
        q[1] = {x:k,y:n}
    }
    function y(p){
        var t = p + (z()*2-1.1)*f
        return (t>h||t<0) ? y(p) : t
    }
    document.onclick = i
    document.ontouchstart = i
    i()
</script>
```