orientationParallax.js

var orientationEls = doc.querySelectorAll('.js-orientation');

window.addEventListener('deviceorientation', function(eventData) {
  var yTilt = Math.round((-eventData.beta + 90) * (40/180) - 40);
  var xTilt = Math.round(-eventData.gamma * (20/180) - 20);

  if (xTilt > 0) {
    xTilt = -xTilt;
  } else if (xTilt < -40) {
    xTilt = -(xTilt + 80);
  }

  Array.from(orientationEls, function (el) {
    window.requestAnimFrame(function () {
      el.style.transform = 'translate(' + xTilt + 'px, ' + yTilt + 'px)';
    });
  });
}, false);