https://adrianmejia.com/most-popular-algorithms-time-complexity-every-programmer-should-know-free-online-tutorial-course/#Power-Set

powerset.js

function powerset(n = '') {
  const array = Array.from(n);
  const base = [''];

  const results = array.reduce((previous, element) => {
    const previousPlusElement = previous.map(el => {
      return `${el}${element}`;
    });
    return previous.concat(previousPlusElement);
  }, base);

  return results;
}