Set.js

'use strict';

/**
 * Provides extensions to the built-in `Set`.
 * @class
 */
module.exports = class Set extends Set {
  /**
   * Returns a `Set` composed of the elements in the
   * current `Set` and a given `set`.
   * @argument {Set}
   * @return {Set}
   */
  union(set) {
    return new Set([...this, ...set]);
  }
  /**
   * Returns a `Set` whose elements are in either the
   * current `Set` or a given `set`.
   * @argument {Set}
   * @return {Set}
   */
  difference(set) {
    return new Set([...this].filter((v) => !set.has(v)));
  }
  /**
   * Returns a `Set` whose elements are in both the
   * current `Set` and a given `set`.
   * @argument {Set}
   * @return {Set}
   */
  intersection(set) {
    return new Set([...this].filter((v) => set.has(v)));
  }
};