[SCRATCH] Cancellable Intermittent Function

can.js

  function animate(fn) {
    var halted = false;

    var f = function() {
      fn();
      if (!halted) requestAnimationFrame(f);
    }

    f();

    return {
      halt: function() {
        halted = true;
      }
    }
  }

  var control = animate(function() {
    console.log('yes');
  });
  setTimeout(function() {
    control.halt();
  }, 1000)