Node.js 26 — Temporal is finally on by default

Node.js 26 came out on May 5 as the new Current release, and it becomes the next LTS line in October. The headline is a feature JavaScript developers have waited years for: the Temporal API is enabled by default.

Temporal: dates without the pain

Date has been JavaScript's weak spot since 1995: months that start at zero, objects you can change in place, and time zones limited to "local" or "UTC". Temporal replaces it with separate types for separate jobs: plain dates, plain times, exact instants, durations, and dates in a named time zone.

// A calendar date: no time, no time zone, no surprises
const deadline = Temporal.PlainDate.from('2026-10-31')
deadline.add({ months: 1 }).toString() // '2026-11-30'

// The same moment shown in two time zones
const call = Temporal.ZonedDateTime.from('2026-10-09T15:00[Europe/Bratislava]')
call.withTimeZone('America/New_York').toPlainTime().toString() // '09:00:00'

On Node 26 there is no flag or polyfill to add; Temporal is a global. If your code also runs in browsers, check support there before dropping your date library.

New JavaScript from V8 14.6

V8 moves to 14.6, which brings two small but useful additions:

// Upsert: read a key, or create it on first use
const byTag = new Map<string, string[]>()
byTag.getOrInsert('bun', []).push('bun-1-4')
byTag.getOrInsertComputed('vite', () => []).push('vite-8')

// Iterate several iterables as one
for (const id of Iterator.concat(drafts.keys(), published.keys())) {
  // …
}

getOrInsert and getOrInsertComputed also exist on WeakMap. The bundled HTTP client, Undici, moves to 8.0.2.

What breaks

This is a major release, so check these before upgrading:

• http.Server.prototype.writeHeader() is gone; use writeHead().
• The legacy _stream_readable, _stream_writable, _stream_duplex, _stream_transform, _stream_passthrough and _stream_wrap modules are removed. Import from node:stream instead.
• The --experimental-transform-types flag is removed.
• module.register() is now runtime-deprecated and prints a warning.
• NODE_MODULE_VERSION is now 147, so native addons need a rebuild.

Bottom line

Node 26 becomes LTS this month, so it is the version to plan production upgrades around. Test on it now: search your code and dependencies for the removed APIs, rebuild native addons, and start writing new date code with Temporal instead of another Date wrapper.