demo: tranditional implementation of animation

run.js

function run(element, cssProperty, value, duration) {
  var initalValue = parseFloat(window.getComputedStyle(element)[cssProperty]);
  var start = new Date().getTime();

  window.requestAnimationFrame(function step() {
    var progress = new Date().getTime() - start;
    var newValue = bounce(progress, initalValue, parseFloat(value) - initalValue, duration);
    element.style[cssProperty] = newValue + 'px';

    if (progress < duration) {
      window.requestAnimationFrame(step);
    } else {
      element.style[cssProperty] = value + 'px';
    }
  });
}