util.js
function previousSiblings(element) {
  var prev = element.previousSibling;
  var siblings = [];

  while (prev) {
    siblings.push(prev);
    prev = prev.previousSibling;
  }

  return siblings;
}
function previousSiblings(element) {
  var prev = element.previousSibling;
  var siblings = [];

  while (prev) {
    siblings.push(prev);
    prev = prev.previousSibling;
  }

  return siblings;
}
Return all prev siblings
@param  {Element} element
@return {Array.<element>}