ip-validation.md

IP Validation ^{6 Kyu}

^{LINK TO THE KATA - REGULAR EXPRESSIONS ALGORITHMS}

Description

Write an algorithm that will identify valid IPv4 addresses in dot-decimal format. IPs should be considered valid if they consist of four octets, with values between 0 and 255, inclusive.

Valid inputs examples:

Examples of valid inputs:
1.2.3.4
123.45.67.89

Invalid input examples:

1.2.3
1.2.3.4.5
123.456.78.90
123.045.067.089

Notes:

• Leading zeros (e.g. 01.02.03.04) are considered invalid
• Inputs are guaranteed to be a single string

Solutions

const isValidIP = ip => {
  const octets = ip.split('.')

  if (octets.length !== 4) return false

  for (const octet of octets) {
    const octetValue = Number(octet)

    if (isNaN(octetValue)) return false

    if (String(octetValue) !== octet) return false

    if (octetValue < 0 || octetValue > 255) return false
  }

  return true
}

const isValidIP = ip => {
  return /^(([1-9]?\d|1\d\d|2[0-4]\d|25[0-5])(\.(?!$)|$)){4}$/.test(ip)
}