Javascript API Version comparator function

api-version-comparator.js

/**
 *  Compares two given API version strings in base 10. Only numbers separated by a dot (".") are supported.
 *  It compares lhs < rhs and returns the default UNIX comparison identifier:
 *
 *  if lhs < rhs
 *    return -1
 *  else if lhs > rhs
 *    return 1
 *  else
 *    return 0
 */
function compareApiVersions (lhs, rhs) {
  var lhs_tokens = lhs.split('.')
  var rhs_tokens = rhs.split('.')

  lhs_tokens.forEach(function (el) {
    el = parseInt(el, 10)
  })

  rhs_tokens.forEach(function (el) {
    el = parseInt(el, 10)
  })

  for (var i = 0, max = Math.max(lhs_tokens.length, rhs_tokens.length); i < max; i++) {
    // pfm: 0.1 && el: 0.2   => true
    // pfm: 0.1 && el: 0.1.1 => true

    var l = lhs_tokens[i] || 0
    var r = rhs_tokens[i] || 0

    if (l < r) {
      return -1
    }

    if (l > r) {
      return 1
    }
  }

  return 0
}

// Tests

console.log(compareApiVersions("1.1.1", "1.1.1") === 0)
console.log(compareApiVersions("1.1.1", "1.1.1.1") === -1)
console.log(compareApiVersions("1.1.1", "1.1.0.1") === 1)
console.log(compareApiVersions("1.2.1", "1.1.1.1") === 1)
console.log(compareApiVersions("1.2.1", "1.12.1.1") === 1)