jQuery version of insertAdjacentElement (b/c jsdom doesn't doesn't implement)

insertAdjacentElement.js

Element.prototype.insertAdjacentElement = function(position, elem) {
  let _this = this;

  switch (position.toLowerCase()) {
    case 'beforebegin':
      $(_this).before($(elem));
      break;
    case 'afterbegin':
      $(_this).prepend($(elem));
      break;
    case 'beforeend':
      $(_this).append($(elem));
      break;
    case 'afterend':
      $(_this).after($(elem));
      break;
  }
  return elem;
};