Get ips by mask

getAllIpAddresses.js

const int2ip = (ipInt) => (
  (ipInt >>> 24) + '.' + 
  (ipInt >> 16 & 255) + '.' + 
  (ipInt >> 8 & 255) + '.' + 
  (ipInt & 255)
);

const ip2int = (ip) => ip.split('.').reduce(
  (ipInt, octet) => (ipInt << 8) + parseInt(octet, 10), 0
) >>> 0;

const toIntMask = (mask) => parseInt([
  ...[...Array(+mask)].map(_ => 1),
  ...[...Array(32 - mask)].map(_ => 0)
].join(''), 2);

const invertMask = (mask) => parseInt([...Array(32 - mask)]
  .map(_ => 1)
  .join(''), 2);

const getIpInterval = (ip, mask) => {
  const intIp = ip2int(ip);
  const intMask = toIntMask(mask);
  const intInvertedMask = invertMask(mask);

  const minIp = (intIp & intMask);
  const maxIp = (intIp | intInvertedMask);

  return [minIp, maxIp];
}

function getIps(ipString) {
  const [ip, mask] = ipString.split("/");
  const [minIp, maxIp] = getIpInterval(ip, mask);

  for (let i = minIp; i <= maxIp; i++) {
    console.log(int2ip(i));
  }
}

getIps("91.221.31.77/24");