A very crude Darude - Sandstorm for Substack's http://studio.substack.net

gistfile1.js

// Darude - Sandstorm
// For http://studio.substack.net/

return function (t) {

  function sin (x) { return Math.sin(2 * Math.PI * t * x) }

  var b = 0.25;
  var beatFn = t % 1 < b*3 ? fastBeep : sustainedBeep
  var pitch
  var pitchChunk = t % (32*b)
  if (pitchChunk >= 0 && pitchChunk < 0.25) {
    pitch = 800
    beatFn = sustainedBeep
  } else if (pitchChunk >= 4 && pitchChunk < 4.25) {
    beatFn = sustainedBeep
    pitch = 500
  } else if (pitchChunk < 2) {
    pitch = 600
  } else if (pitchChunk < 3) {
    pitch = 800
  } else if (pitchChunk < 4) {
    pitch = 700
  } else if (pitchChunk >= 6 && pitchChunk < 6.25) {
    pitch = 800
    beatFn = sustainedBeep
  } else {
    pitch = 600
  }
   
  function fastBeep() {
    var tb = t % b
    return tb < b/4 || (tb >= b/2 && tb < 3*b/4) ? sin(pitch) : 0
  }

  function sustainedBeep() {
    return t % b < 3*b/5 ? sin(pitch) : 0
  }

  return beatFn();
}