Combinatorics: Good Power Set implementation in ECMAScript

powerset.js

function *powerSet(sourceSet) {
        function product(ones, sourceSet) {
          let l = ones.length;
          let out = new Array(l);
          for (var i = 0; i < l; i++) {
            out[i] = sourceSet[ones[i]]
          }
          return out;
        }

        function getMostSignificant(ones, sourceSet) {
          let k = ones.length - 1;
          const sourceSetLen = sourceSet.length;
          const onesLen = ones.length;
          while (ones[k] == (sourceSetLen - 1) - (onesLen - 1 - k)) k--;
          return k;
        }

        // trivial case
        yield [];

        let l = sourceSet.length;

        for (var setlen = 1; setlen <= l; setlen++) {
          let ones = new Array(setlen);
          for (var i = 0; i < setlen; i++) ones[i] = i;

          yield product(ones, sourceSet);

          if (setlen == l) return;

          const lastDigit = setlen - 1;

          while ('💃🏾') {
            ones[lastDigit] = ones[lastDigit] + 1;
            if (ones[lastDigit] > l - 1) {
              ones[lastDigit] = l - 1;
              const k = getMostSignificant(ones, sourceSet);
              if (k == -1) break;
              ones[k] = ones[k] + 1
              for (var m = k + 1; m < setlen; m++) ones[m] = ones[m-1] + 1;
            }
            yield product(ones, sourceSet);
          }
        }
      }