function powNaive(x, y) {

    if (!y) return 1;

    let tmp = x;

    for (let i = 1; i < y; i++) {

        tmp *= x;

    }

    return tmp;

}

​

// from https://codereview.stackexchange.com/a/217369

function pow2B(x, y) {

    if (y < 2) { return y ? x : 1 }

    if (y & 1) { return x * pow2B(x, y & 0x7FFFFFFE)}

    const p = pow2B(x, y >> 1);

    return p * p;

}

​

// other two functions from the same stackexchange post

function pow(x, y) {

  if (!y) { return 1 }

  let tmp = res = x;

  for (let i = 1; i < y; i++) {

    for (let j = 1; j < x; j++) { tmp += res }

    res = tmp;

  }

  return res;

}

​

function pow2(x, y) {

  if (!y) { return 1; }

  if (y % 2) {

    return x * pow2(x, y - 1);

  }

  const p = pow2(x, y/2);

  return p * p;

}