Egyptian multifying

const half = n => n >>> 1;
const odd = n => !!(n & 0x1);
const even = n => !!!(odd(n));

const multify1 = (a, b, doubled) => {
  doubled = doubled + 1;
  if (a === 1) return b;
  res = multify1(half(a), b + b, doubled);
  if (odd(a)) res = res + b;
  console.info('[multiFy1]Interim result', a, b, 'doubled', doubled, 'times returns', res);
  return res;
};

const mult_acc0 = (r, n, a) => {
  if (n === 1) return r + a;
  if (odd(n)) {
    return mult_acc0(r + a, half(n), a + a);
  } else {
    return mult_acc0(r, half(n), a + a);
  }
};

const mult_acc1 = (r, n, a) => {
  if (n == 1) return r + a;
  if (odd(n)) r = r + a;
  return mult_acc0(r, half(n), a + a);
};

const mult_acc2 = (r, n, a) => {
  if (odd(n)) {
    r = r + a;
    if (n === 1) return r;
  }
  return mult_acc2(r, half(n), a + a);
};

const mult_acc3 = (r, n, a) => {
  if (odd(n)) {
    r = r + a;
    if (n === 1) return r;
  }
  n = half(n);
  a = a + a;
  return mult_acc3(r, n, a);
};

const mult_acc4 = (r, n, a) => {
  while (true) {
    if (odd(n)) {
      r = r + a;
      if (n === 1) return r;
    }
    n = half(n);
    a = a + a;
  }
};

const multify2 = (n, a) => {
  if (n === 1) return a;
  return mult_acc4(a, n - 1, a);
};

const multify3 = (n, a) => {
  while (even(n)) {
    a = a + a;
    n = half(n);
  }
  if (n === 1) {
    console.log('pre looped', a, n);
    return a;
  }
  return mult_acc4(a, n - 1, a);
};

const multify4 = (n, a) => {
  while (even(n)) {
    a = a + a;
    n = half(n);
  }  
  if (n === 1) {
    console.log('pre looped', a, n);
    return a;
  }
  return mult_acc4(a, half(n - 1), a + a);
};

console.log('[multify1] result: ', multify1(17, 13, 0));
console.log('[mult_acc0] result:', mult_acc0(0, 17, 13));
console.log('[mult_acc1] result:', mult_acc1(0, 17, 13));
console.log('[mult_acc2] result:', mult_acc2(0, 17, 13));
console.log('[mult_acc3] result:', mult_acc3(0, 17, 13));
console.log('[mult_acc4] result:', mult_acc4(0, 17, 13));
console.log('[multify2] result: ', multify2(17, 12, 0));
console.log('[multify3] result: ', multify3(16, 15, 0));
console.log('[multify3] result: ', multify3(15, 16, 0));
console.log('[multify4] result: ', multify4(16, 15, 0));
console.log('[multify4] result: ', multify4(15, 16, 0));