cross browser requestAnimationFrame that works like setInterval (returns a function that will stop loop if called)

raf.js

module.exports = animate

var requestAnimationFrame =
  global.requestAnimationFrame ||
  global.webkitRequestAnimationFrame ||
  global.mozRequestAnimationFrame ||
  global.msRequestAnimationFrame ||
  global.oRequestAnimationFrame ||
  function(fn, el) {
    setTimeout(fn, 1000/60)
  }

function animate(tick, el){
  animating = true
  requestAnimationFrame(iter, el)
  function iter(timestamp) {
    if (animating){
      tick()
      requestAnimationFrame(iter, el)
    }
  }

  return function(){
    animating = false
  }
}