Javascript powerset function

power set

const _ = require('lodash');

function supersetInner(src) {
  if (src.length === 0) return [];

  const withouts = _.map(src, elem => superset(_.without(src, elem)));
  return [src, ..._.flatten(withouts)];
}

function superset(src) {
  return _.uniqWith(supersetInner(src), _.isEqual).sort();
}

console.log(JSON.stringify(superset([1, 2, 3, 4])));