First things first, why 4.0.0? Most users of Node are using a version that hasn’t yet hit 1.0. I don’t want to get far into the weeds on this issue, but the nutshell explanation is that last year Node was forked into a couple of competing versions: Node.js, which was overseen by Node’s original creators Joyent, and io.js, which was a community project. The fork occurred because the community was unhappy with the pace of development.
Earlier this year, Joyent handed management of Node over to a new foundation and io.js was merged into the foundation. The name is Node.js again, but the Io.js project used a different versioning scheme and their most recent release was 3.0. Rather than confuse the issue, Node will be moving forward from 4.0.0. Node 4.0.0 is the stable version, and it’s the one that most developers should use.
(It’s 4.0.0 rather than 4 or 4.0 because Node now uses semantic versioning).
What’s New In Node?
The obvious direct advantage of an updated version of V8 is increased performance. Node has always been fast, and now it’s faster.
It’s worth noting that the new V8 version will break some Node modules — specifically the small proportion of “native” modules that are written in C++ and linked against a particular V8 version (or rather the abstraction library Nan). If something breaks when you update, this may well be the reason, but it’s likely that modules will be rebuilt for the new version quite quickly.
ECMAScript 6 Features
There are several other language changes that come along with ES6. You can see the full list here.
A More Predictable Release Cycle
Node is now serious business, with great uptake in the enterprise — an environment that prefers predictability. The Node team will be making LTS — Long Term Support — releases every 12 months, and each LTS version will be active for 12 months and maintained for another 18, which gives companies a predictable 30-month cadence of release lifespans.
If you’re using Node, the branch starting at Node 4.0.0 is the one you should follow for future releases and improvements.