List of list combinations

recursive_combinations.js

// thanks @david

var arrays = [[1], [1], [1,2], [1]];
function combos(list, currentIndex = 0, combinations = [], current = []) {
  if (currentIndex === list.length) {
    combinations.push(current);
  } else {
    for (var item of list[currentIndex]) {
      combos(list, currentIndex + 1, combinations, [...current, item]);
    }
  }
  return combinations;
}

console.log(combos(arrays));
// 0: [1, 1, 1, 1]
// 1: [1, 1, 2, 1]