index.js

/**
 * Expose `requestAnimationFrame()`.
 */

exports = module.exports = window.requestAnimationFrame
  || window.webkitRequestAnimationFrame
  || window.mozRequestAnimationFrame
  || fallback;

/**
 * Fallback implementation.
 */

var prev = new Date().getTime();
function fallback(fn) {
  var curr = new Date().getTime();
  var ms = Math.max(0, 16 - (curr - prev));
  var req = setTimeout(fn, ms);
  prev = curr;
  return req;
}

/**
 * Cancel.
 */

var cancel = window.cancelAnimationFrame
  || window.webkitCancelAnimationFrame
  || window.mozCancelAnimationFrame
  || window.clearTimeout;

exports.cancel = function(id){
  cancel.call(window, id);
};