Javascript Array intersect(otherArray)

/**// w w  w  .j  a  va  2s  .c  o m
 * Compare this array with another one and return an array with all the items
 * that are in both arrays.
 * 
 * @param {Array} otherArray The array to compare to
 * @return {Array} An array with all items in this array and otherArray
 */
Array.prototype.intersect = function intersect(otherArray) {
 return this.filter(function(item) {
  return otherArray.has(item);
 });
};