Semantic version comparison via https://github.com/lambci/lambci/blob/942cca1b695b877f0dbeff8283c54d1e765ce46c/utils/index.js#L86

semver-regex.js

//              NUM            . NUM            . NUM            -beta.3.4 (optional)           +build.meta.data (ignore)
var SEMVER = /^(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)(-[\da-z-]+(?:\.[\da-z-]+)*)?(?:\+[\da-z-]+(?:\.[\da-z-]+)*)?$/i
var SIMPLE_NUMBER = /^(0|[1-9][0-9]*)$/

function semverCmp(ver1, ver2) {
  if (ver1 === ver2) return 0
  var match1 = ver1.match(SEMVER), match2 = ver2.match(SEMVER)
  if (!match1) return match2 ? 1 : 0
  if (!match2) return -1
  for (var i = 1; i <= 3; i++) {
    var num1 = +match1[i], num2 = +match2[i]
    if (num1 < num2) return -1
    if (num1 > num2) return 1
  }
  if (!match1[4]) return match2[4] ? 1 : 0
  if (!match2[4]) return -1
  var preRels1 = match1[4].slice(1).split('.'), preRels2 = match2[4].slice(1).split('.')
  for (i = 0; i < Math.max(preRels1.length, preRels2.length); i++) {
    var preRel1 = SIMPLE_NUMBER.test(preRels1[i]) ? +preRels1[i] : preRels1[i]
    var preRel2 = SIMPLE_NUMBER.test(preRels2[i]) ? +preRels2[i] : preRels2[i]
    if (i >= preRels1.length || (typeof preRel2 == 'string' && typeof preRel1 == 'number')) return -1
    if (i >= preRels2.length || (typeof preRel1 == 'string' && typeof preRel2 == 'number')) return 1
    if (preRel1 < preRel2) return -1
    if (preRel1 > preRel2) return 1
  }
  return 0
}