js-fade-gradient

fade-gradient.js

function updateGradient() {
  var a = colors[colorIndices[0]],
      b = colors[colorIndices[1]],
      c = colors[colorIndices[2]],
      d = colors[colorIndices[3]],
      e = 1 - step,
      f = Math.round(e * a[0] + step * b[0]),
      g = Math.round(e * a[1] + step * b[1]),
      h = Math.round(e * a[2] + step * b[2]),
      i = "#" + (f << 16 | g << 8 | h).toString(16),
      j = Math.round(e * c[0] + step * d[0]),
      k = Math.round(e * c[1] + step * d[1]),
      l = Math.round(e * c[2] + step * d[2]),
      m = "#" + (j << 16 | k << 8 | l).toString(16);
  $gradientContainer.css({
    background: "-webkit-gradient(linear, left top, right top, from(" + i + "), to(" + m + "))"
  }).css({
    background: "-moz-linear-gradient(left, " + i + " 0%, " + m + " 100%)"
  }), step += gradientSpeed, step >= 1 && (step %= 1, colorIndices[0] = colorIndices[1], colorIndices[2] = colorIndices[3], colorIndices[1] = (colorIndices[1] + Math.floor(1 + Math.random() * (colors.length - 1))) % colors.length, colorIndices[3] = (colorIndices[3] + Math.floor(1 + Math.random() * (colors.length - 1))) % colors.length)
}
var colors = new Array([62, 35, 255], [60, 255, 60], [255, 35, 98], [45, 175, 230], [255, 0, 255], [255, 128, 0]),
    step = 0,
    colorIndices = [0, 1, 2, 3],
    gradientSpeed = .001,
    $gradientContainer = $('__CONTAINER__');
setInterval(updateGradient, 100);

source:
https://d340syr2dan8gj.cloudfront.net/assets/app/gallery/connect-26ef0c356bb1648c500d3ed04b4abf59.js