code: function ariaRangeValue(node) {
  	node = node.actualNode || node;
  	const role = aria.getRole(node);
  	if (!rangeRoles.includes(role) || !node.hasAttribute('aria-valuenow')) {
  		return '';
  	}
  	// Validate the number, if not, return 0.
  	// Chrome 70 typecasts this, Firefox 62 does not
  	const valueNow = +node.getAttribute('aria-valuenow');
  	return !isNaN(valueNow) ? String(valueNow) : '0';
  }
docs: Calculate value of an element with range-type role
  
  @param {VirtualNode|Node} element The VirtualNode instance whose value we want
  @return {string} The calculated value