utility.js

function includes(array, obj) {
  return Array.prototype.indexOf.call(array, obj) != -1;
}

function arrayRemove(array, value) {
  var index = array.indexOf(value);
  if (index >= 0) {
    array.splice(index, 1);
  }
  return index;
}

/**
 * @param   {Element}     el
 * @param   {string}      selector
 * @return  {Element[]}
 */

h.children = function(el, selector) {
    var selectors      = null,
        children       = null,
        childSelectors = [],
        tempId         = '';

    selectors = selector.split(',');

    if (!el.id) {
        tempId = '_temp_';

        el.id = tempId;
    }

    while (selectors.length) {
        childSelectors.push('#' + el.id + '>' + selectors.pop());
    }

    children = document.querySelectorAll(childSelectors.join(', '));

    if (tempId) {
        el.removeAttribute('id');
    }

    return children;
};

/**
 * @param   {Element}       el
 * @param   {string}        selector
 * @param   {boolean}       [includeSelf]
 * @return  {Element|null}
 */

h.closestParent = function(el, selector, includeSelf) {
    var parent = el.parentNode;

    if (includeSelf && el.matches(selector)) {
        return el;
    }

    while (parent && parent !== document.body) {
        if (parent.matches && parent.matches(selector)) {
            return parent;
        } else if (parent.parentNode) {
            parent = parent.parentNode;
        } else {
            return null;
        }
    }

    return null;
};

/**
 * @param   {Element}   el
 * @param   {string}    [selector]
 * @return  {number}
 */

h.index = function(el, selector) {
    var i = 0;

    while ((el = el.previousElementSibling) !== null) {
        if (!selector || el.matches(selector)) {
            ++i;
        }
    }

    return i;
};