feat: latestOfMajorOnly option to restrict to latest of each major line

index.d.ts

@@ -2,6 +2,7 @@ interface Options {
   now?: Date;
   cache?: Map<any, any>;
   mirror?: string;
+  latestOfMajorOnly?: Boolean
 }
 
 interface VersionInfo {

index.js

@@ -7,12 +7,13 @@ module.exports = async function (alias = 'lts_active', opts = {}) {
   const now = opts.now || new Date()
   const cache = opts.cache || _cache
   const mirror = opts.mirror || 'https://nodejs.org/dist/'
+  const latestOfMajorOnly = opts.latestOfMajorOnly || false
 
   const a = Array.isArray(alias) ? alias : [alias]
   const versions = await getLatestVersionsByCodename(now, cache, mirror)
 
   // Reduce to an object
-  const m = a.reduce((m, a) => {
+  let m = a.reduce((m, a) => {
     const vers = resolveAlias(versions, a)
     if (Array.isArray(vers)) {
       vers.forEach((v) => {
@@ -24,6 +25,18 @@ module.exports = async function (alias = 'lts_active', opts = {}) {
     return m
   }, {})
 
+  // If only latest major is true, filter out all but latest
+  if (latestOfMajorOnly) {
+    const vers = Object.values(m).reduce((latestMajor, v) => {
+      // If highest in version range, save off
+      if (!latestMajor[v.major] || semver.gt(v.version, latestMajor[v.major].version)) {
+        latestMajor[v.major] = v
+      }
+      return latestMajor
+    }, {})
+    m = Array.from(Object.values(vers))
+  }
+
   // Sort and pluck version
   return Object.values(m).sort((v1, v2) => {
     return semver.gt(v1.version, v2.version) ? 1 : -1

index.test-d.ts

@@ -7,6 +7,7 @@ import nv from '.'
   await nv(['lts_active'], {
     now: new Date(),
     cache: new Map(),
-    mirror: 'http://example.com'
+    mirror: 'http://example.com',
+    latestOfMajorOnly: true
   })
 })()

test/index.js

@@ -132,4 +132,10 @@ suite('nv', () => {
     assert.strictEqual(versions[0].tag, 'v8-canary20191022e5d3472f57')
     assert.strictEqual(versions[0].versionName, 'v13')
   })
+
+  test('latestOfMajorOnly', async () => {
+    const versions = await nv('18.x', { now, latestOfMajorOnly: true })
+    assert.strictEqual(versions.length, 1)
+    assert.strictEqual(versions[0].major, 18)
+  })
 })