Restore IP coding challenge (fun with Pancho)

eleganterRestoreIp.ts

function* restore(raw: string, ip = ''): Generator {
  if (raw.length === 0)
    yield ip.slice(1);
  for (const i of [0, 1, 2]) {
    const octet = raw.slice(0, i+1);
    if (i >= raw.length
      || Number(octet) > 255
      || ip.split('.').length > 4
      || octet.length > 1 && octet[0] === '0'
    ) continue;
    yield* restore(raw.slice(i+1), `${ip}.${octet}`);
  }
}

console.log([...restore('12345678')]);

restore-ip.hoon

|=  raw=tape
^-  ~
=/  ip  ""
|-
?~  `*`raw
  ~&  `tape`(slag 1 ip)  ~
=<  ~ 
%+  turn
  %+  gulf  0
  (min 2 (dec (lent raw)))
|=  i=@ud
=/  octet  (swag [0 +(i)] raw)
?:
    ?|
      (gth `@ud`(slav %ud (crip octet)) 255)
      (gth (lent (fand ~['.'] ip)) 3)
    ==
  ~
%=  ^$
raw  (slag +(i) raw)
ip   "{ip}.{octet}"
==

restoreIp.ts

const isValidIp = (ip: string) => {
  const octets = ip.slice(1).split('.')
  if (octets.length !== 4) {
    return false;
  }
  return octets.every(octet => {
    const noLeadingZero = (octet.length > 1 && octet[0] !== '0') || octet.length === 1;
    const isEightBits = Number(octet) < 256;
    return isEightBits && noLeadingZero;
  })
}

const restoreIp = (corruptedIp: string, newIp = ''): string[] => {
  let [firstDigit, secondDigit, thirdDigit] = corruptedIp.split('');
  switch (corruptedIp.length) {
    case 0:
      return [newIp];
    case 1:
      return [`${newIp}.${corruptedIp}`];
    case 2:
      return [
        `${newIp}.${corruptedIp}`,
        `${newIp}.${firstDigit}.${secondDigit}`
      ]
    default:
      const smallOctet = restoreIp(
        corruptedIp.slice(1),
      `${newIp}.${firstDigit}`
      );
      const mediumOctet = restoreIp(
        corruptedIp.slice(2),
        `${newIp}.${firstDigit+secondDigit}`
      );
      const bigOctet = restoreIp(
        corruptedIp.slice(3),
        `${newIp}.${firstDigit+secondDigit+thirdDigit}`
      );
      return smallOctet
        .concat(mediumOctet)
        .concat(bigOctet)
        .filter(isValidIp);
  }
  return ['anything below this line is dead code!']
}

console.log(restoreIp('12345678'))

Based on this challenge intended for Hoon: https://docs.urbit.org/language/hoon/examples/restore-ip

Finally added Hoon version! I think my solution is way simpler than the official solutions.