Compare semantic versions

compare-versions.js

module.exports = function(a, b) {
    const vA = /^(\d+)\.(\d+)(?:\.(\d+))?(.*)$/.exec(a),
          vB = /^(\d+)\.(\d+)(?:\.(\d+))?(.*)$/.exec(b)

    // Invalid version number go at the end
    if (vA == null) return -1
    if (vB == null) return 1

    // Numeric version components
    const nA = (vA[1] >>> 0) * 10000 + (vA[2] >>> 0) * 100 + (vA[3] >>> 0),
          nB = (vB[1] >>> 0) * 10000 + (vB[2] >>> 0) * 100 + (vB[3] >>> 0)

    if (nA < nB) return -1
    if (nA > nB) return 1

    // Same numeric version: compare stage names
    const sA = vA[4],
          sB = vB[4]

    // Same stage name (or lack thereof)
    if (sA === sB) return 0

    // No stage name for? Final versions come last
    if (!sA) return 1
    if (!sB) return -1

    // Sort stage names lexicographically
    return [sA, sB].sort()[0] === sA ? -1 : 1
}