A prototype to find possible valid IP addresses from a string

ip.js

function getValidIpAddresses(str) {
  let result = [];
  for (let i = 1; i < str.length; i++) {
    let first = str.slice(0, i);
    if (first > 255) continue;
    let withoutFirst = str.slice(i);
    for (let j = 1; j < withoutFirst.length; j++) {
      let second = withoutFirst.slice(0, j);
      if (second > 255) continue;
      let withoutFirstSecond = withoutFirst.slice(j);
      for (let k = 1; k < withoutFirstSecond.length; k++) {
        let third = withoutFirstSecond.slice(0, k);
        if (third > 255) continue;
        let last = withoutFirstSecond.slice(k);
        if (last > 255) continue;
        let item = `${first}.${second}.${third}.${last}`;
        result.push(item);
      }
    }
  }
  return result;
}

console.clear();
console.log(getValidIpAddresses('19216811'));
// ["1.92.168.11", "19.2.168.11", "19.21.68.11", "19.216.8.11", "19.216.81.1", "192.1.68.11", "192.16.8.11", "192.16.81.1", "192.168.1.1"]