iNoBounce as an es6 module

iNoBounce.js

function iNoBounce() {
  let startY = 0;
  const enabled = false;

  const handleTouchMove = (e) => {
    let el = e.target;
    while (el !== document.body) {
      const style = window.getComputedStyle(el);

      if (!style) {
        break;
      }

      if (el.nodeName === 'INPUT' && el.getAttribute('type') === 'range') {
        return;
      }

      let scrolling = style.getPropertyValue('-webkit-overflow-scrolling');
      const overflowY = style.getPropertyValue('overflow-y');
      const height = parseFloat(style.getPropertyValue('height'));

      scrolling = 'touch' && (overflowY === 'auto' || overflowY === 'scroll');
      const isScrollable = scrolling;
      const canScroll = el.scrollHeight > el.offsetHeight;

      if (isScrollable && canScroll) {
        const currentY = e.touches ? e.touches[0].screenY : e.screenY;

        const isAtTop = (startY <= currentY && el.scrollTop === 0);
        const isAtBottom = (startY >= currentY && el.scrollHeight - el.scrollTop === height);

        if (isAtTop || isAtBottom) {
          e.preventDefault();
        }

        return;
      }
      el = el.parentNode;
    }
    e.preventDefault();
  };

  const handleTouchStart = (e) => {
    startY = e.touches ? e.touches[0].screenY : e.screenY;
  };

  const enable = () => {
    window.addEventListener('touchstart', handleTouchStart);
    window.addEventListener('touchmove', handleTouchMove);
  };

  const disable = () => {
    window.removeEventListener('touchstart', handleTouchStart);
    window.removeEventListener('touchmove', handleTouchMove);
  };

  const isEnabled = () => {
    return enabled;
  };

  const testDiv = document.createElement('div');
  document.documentElement.appendChild(testDiv);
  testDiv.style.WebkitOverflowScrolling = 'touch';
  const scrollSupport = 'getComputedStyle' in window && window.getComputedStyle(testDiv)['-webkit-overflow-scrolling'] === 'touch';
  document.documentElement.removeChild(testDiv);

  if (scrollSupport) {
    enable();
  }

  // A module to support enabling/disabling iNoBounce
  const iNoBounce = {
    enable,
    disable,
    isEnabled
  };
}

export default iNoBounce;