js从字符串找到一个合法的ip

function resolveIp(str) {
  const result = []
  if (str.length < 4 && str.length > 12) {
    return result
  }
  for (let a = 1; a < 4; a++) {
    for (let b = 1; b < 4; b++) {
      for (let c = 1; c < 4; c++) {
        const d = str.length - a - b - c
        if (d >= 1 && d <= 3) {
          const one = str.substring(0, a)
          const tow = str.substring(a, a + b)
          const there = str.substring(a + b, a + b + c)
          const four = str.substring(a + b + c)
          if (isValid(one) && isValid(tow) && isValid(there) && isValid(four)) {
            result.push(`${one}.${tow}.${there}.${four}`)
          }
        }
      }
    }
  }
  return result
}
function isValid (str) { 
  // 1. 值等于0 的时候 长度为1
  const  one = +str === 0 && str.length === 1
  // 2.值大于0  第一个字符不能为0
  const two = +str > 0 && str.charAt(0) !== '0'
  // 值要小于等于255
  const there = +str <= 255
  return (one || two) && there
}

const result1 = resolveIp('2552551125')
const result2 = resolveIp('1110110')
console.log('result1', result1)
console.log('result2', result2)