wave.js

window.requestAnimFrame = (function() {
    return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || function(a) {
        window.setTimeout(a, 1000 / 60)
    }
})();
window.onload = function() {
    var m = canvas.getContext("2d"),
        k, g;
    canvas.width = k = window.innerWidth * 2.1;
    canvas.height = g = window.innerHeight * 1.4;
    var i = new j(),
        e = new j(),
        c = new j(),
        b = g * 0.5;
    count = 40, step = Math.ceil(k / count), buffer = new ArrayBuffer(count * 4), points = new Float32Array(buffer);
    i.max = 15;
    e.max = 5;
    e.speed = 0.03;
    e.max = 5;
    e.speed = 0.015;

    function l() {
        for (var h = 0; h < count; h++) {
            points[h] = a(i, e, c)
        }
    }
    l();
    m.lineWidth = 20;
    m.strokeStyle = "#393d46";
    m.fillStyle = "#393d46";

    function f() {
        var h;
        for (h = 0; h < count - 1; h++) {
            points[h] = points[h + 1]
        }
        points[count - 1] = a(i, e, c);
        m.clearRect(0, 0, k, g);
        m.beginPath();
        m.moveTo(-5, points[0]);
        for (h = 1; h < count; h++) {
            m.lineTo(h * step, points[h])
        }
        m.lineTo(k, g);
        m.lineTo(-5, g);
        m.lineTo(-5, points[1]);
        m.stroke();
        m.fill()
    }

    function j() {
        this.variation = 0.4;
        this.max = 150;
        this.speed = 0.02;
        var o = this,
            n = 0,
            h = p();
        this.getAmp = function() {
            n += this.speed;
            if (n >= 2) {
                n = 0;
                h = p()
            }
            return h * Math.sin(n * Math.PI)
        };

        function p() {
            return Math.random() * o.max * o.variation + o.max * (1 - o.variation)
        }
        return this
    }

    function a() {
        var o = arguments.length,
            h = o,
            n = 0;
        if (o < 1) {
            return 0
        }
        while (h--) {
            n += arguments[h].getAmp()
        }
        return n / o + b
    }(function d() {
        requestAnimFrame(d);
        f()
    })()
};