Coroutines in Javascript

babysitter.js

var babysitter = {
  coroutines : []
}

babysitter.add = function(c)
{
  // add a new coroutine to be "babysat"
  babysitter.coroutines.push(c());
}

babysitter.clear = function()
{
  // remove all the coroutines, start afresh
  babysitter.coroutines.length = 0;
}

babysitter.countRunning = function()
{
  return babysitter.coroutines.length;
}

babysitter.update = function(dt)
{
  // this is where I'd really love J. Blow's 'remove' primitive...
  var i = 0;
  while(i < babysitter.coroutines.length)
  {
    var c = babysitter.coroutines[i];
    // this passes delta-time to the coroutine using magic
    var done = c.next(dt).done;
    // remove any couroutines that have finished
    if(done)
      babysitter.coroutines.splice(i, 1);
    else
      i++;
  }
}

babysitter.waitForSeconds = function*(duration_s) {
  var duration_ms = duration_s * 1000;
  var start_ms = Date.now();
  var dt = 0;
  while (Date.now() - start_ms < duration_ms)
    dt = yield undefined;
  return dt;
}

main.js

  window.onload = function() {
    
    var lastFrameTime = Date.now();
    function nextFrame() {
      var thisFrameTime = Date.now();
      var deltaTime = thisFrameTime - lastFrameTime;
      lastFrameTime = thisFrameTime;
      babysitter.update(deltaTime);
      requestAnimationFrame(nextFrame);
    }
    nextFrame();
      
    babysitter.add(function*(dt) {
      dt = yield undefined;
      for(var i = 0; i < 10; i++)
      {      
        dt = yield * babysitter.waitForSeconds(1.0);
        console.log(i, "this frame's delta time:", dt);
      }      
    });
  }

Live demo on jsfiddle :)

Is this code under a specifique licence ? MIT ? CC0 ? private ?