Quick-and-Dirty `Set` implementation

quick-and-dirty-set.js

// Quick-and-Dirty `Set` implementation.
/* eslint-disable */
export const Set = global.Set || function (a = []) {
  a = a.filter((x, i) => i === a.indexOf(x));
  a.size = a.length;
  a.has = x => a.indexOf(x) > -1;
  a.add = x => { if (!a.has(x)) { a.size++; a.push(x); } return a; };
  a.delete = x => { let t; if (t = a.has(x)) { a.size--; delete a[a.indexOf(x)]; } return t; };
  a.keys = a.values = () => a[Symbol.iterator]();
  a.clear = () => { while (a.pop()) {} a.size = 0; };
  return a;
};
/* eslint-enable */