Limit the frame-rate being targeted with requestAnimationFrame

AnimationFrame.js

/*
http://cssdeck.com/labs/embed/gvxnxdrh/0/output
http://codetheory.in/controlling-the-frame-rate-with-requestanimationframe/
*/
class AnimationFrame {
  constructor(fps = 60, animate) {
    this.requestID = 0;
    this.fps = fps;
    this.animate = animate;
  }

  start() {
    let then = performance.now();
    const interval = 1000 / this.fps;

    const animateLoop = (now) => {
      this.requestID = requestAnimationFrame(animateLoop);
      const delta = now - then;

      if (delta > interval) {
        then = now - (delta % interval);
        this.animate(delta);
      }
    };
    this.requestID = requestAnimationFrame(animateLoop);
  }

  stop() {
    cancelAnimationFrame(this.requestID);
  }

}