powerset.js

const powerSet = (array) => {
  const results = [];

  const maximum = 1 << array.length;
  let reference = 0;

  while (reference < maximum) {
    results.push(array.filter((element, index) => reference & 1 << index));
    reference++;
  }

  return results;
};


const powerSetRecursive = ([first, ...rest]) => {
  if (rest.length === 0) {
    return [[], [first]];
  }
  const results = powerSetRecursive(rest);
  return results.concat(results.map(element => [first, ...element]));
};


const test = array => {
  const result = powerSet(array);
  const recursive = powerSetRecursive(array);
  console.log(result);
  console.log(recursive);
  console.log(result.length === 2 ** array.length);
  console.log(result.length === recursive.length);
};

test([1, 2, 3, 4, 5, 10])