util.js

'use strict'; // filter function for ancestor elements

var filterAncestor = function filterAncestor(item) {
  return item.nodeType === 1 && item.tagName.toLowerCase() !== 'body' && item.tagName.toLowerCase() !== 'html';
}; // filter function for sibling elements


var filterSibling = function filterSibling(item) {
  return item.nodeType === 1 && item.tagName.toLowerCase() !== 'script';
}; // reducer to flatten arrays


var flattenArrays = function flattenArrays(a, b) {
  return a.concat(b);
}; // recursive function to get previous sibling nodes of given element


function getPreviousSiblings(el) {
  var siblings = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : [];
  var previousSibling = el.previousSibling;

  if (!previousSibling) {
    return siblings;
  }

  siblings.push(previousSibling);
  return getPreviousSiblings(previousSibling, siblings);
} // recursive function to get next sibling nodes of given element


function getNextSiblings(el) {
  var siblings = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : [];
  var nextSibling = el.nextSibling;

  if (!nextSibling) {
    return siblings;
  }

  siblings.push(nextSibling);
  return getNextSiblings(nextSibling, siblings);
} // returns all sibling element nodes of given element


function getSiblings(el) {
  var allSiblings = getPreviousSiblings(el).concat(getNextSiblings(el));
  return allSiblings.filter(filterSibling);
} // recursive function to get all ancestor nodes of given element


function getAllAncestors(el) {
  var ancestors = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : [];
  var nextAncestor = el.parentNode;

  if (!nextAncestor) {
    return ancestors;
  }

  ancestors.push(nextAncestor);
  return getAllAncestors(nextAncestor, ancestors);
} // get ancestor nodes of given element


function getAncestors(el) {
  return getAllAncestors(el).filter(filterAncestor);
} // get siblings of ancestors (i.e. aunts and uncles) of given el


function getSiblingsOfAncestors(el) {
  return getAncestors(el).map(function (item) {
    return getSiblings(item);
  }).reduce(flattenArrays, []);
}

module.exports = {
  getSiblings: getSiblings,
  getAncestors: getAncestors,
  getSiblingsOfAncestors: getSiblingsOfAncestors
};