Simple function to determine whether a given ip is within a range of ip addresses.

is-ip-in-ip-range.js

const ipRegex = /([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})/
const getIpDigits = (ip) => {
  const digits = ipRegex.exec(ip)
  if (!digits) {
    return [-1, -1, -1, -1]
  }
  
  return ipRegex.exec(ip).splice(1).map(stringDigit => +stringDigit)
}

//Ranges for AlertLogic testing servers
const ranges = [
  [ '204.110.218.0', '204.110.219.255' ],
  [ '208.71.208.0',  '208.71.211.255'  ],
  [ '185.54.124.0',  '185.54.127.255' ]
]
.map(([ start, end ]) => [ getIpDigits(start), getIpDigits(end) ])

const ipIsInKnownRange = ip => {
  const ipDigits = getIpDigits(ip)

  return ranges.some(([start, end]) => {
    return start.every((digit, digitIdx) => ipDigits[digitIdx] >= digit)
      && end.every((digit, digitIdx) => ipDigits[digitIdx] <= digit)
  })
}

Example usage:

if (ipIsInKnownRange('192.168.0.1')){
  console.log("yup")
}