Functional IP Validator

ipValidator.js

const toInteger = digitString => parseInt(digitString)
const isValidInteger = digit => !isNaN(digit)
const isGreaterOrEqualThan = n1 => n2 => n1 >= n2
const isLessOrEqualThan = n1 => n2 => n1 <= n2

const isValidIp = ip => ip
    .split(".")
    .map(toInteger)
    .filter(isValidInteger)
    .filter(isGreaterOrEqualThan(255))
    .filter(isLessOrEqualThan(0))
    .length === 4

console.log(isValidIp("0.0.0.0"))
console.log(isValidIp("192.168.1.1"))
console.log(isValidIp("") )
console.log(isValidIp("1.1.1") )
console.log(isValidIp("a.a.a.a") )
console.log(isValidIp("192.168.1.999") )
console.log(isValidIp("192.168.1.-1") )