Breaking Changes
Through 2.x, if Buffer.concat is invoked with a single element array, then it will simply return the first element from it. But, starting from 3.0.0, irrespective of the number of elements in the array, a new Buffer object will be created and returned.
Through 2.x, the the dgram socket.send() method emitted errors when a DNS lookup failed, even when a callback was provided. Starting from 3.0.0, if a callback is provided, no error event will be emitted.
Refs: #1796
Somehow this is marked as semver-major?? https://github.com/nodejs/io.js/commit/6020d2a2fb75de6766c807864fa8f1c0fba88ec9 https://github.com/nodejs/io.js/pull/1411 Someone help.
The upgrade from V8 4.2 to 4.3 will require a recompile of all native add-ons. The API surface area has not changed significantly, so most add-ons will "just work" after a recompile.
However, 4.3 introduces the new Maybe<> and MaybeLocal<> types, to fix systemic use-after-failure bugs where consumers could accidentally use empty handles. Many new APIs were introduced that return these types and take a Context argument. Add-on authors are encouraged to transition to these new maybe-style APIs as soon as possible, as V8 has deprecated the old ones and will eventually remove them.
os.tmpdir() has been changed to never return a trailing slash regardless of the host platform.
The upgrade from V8 4.1 to 4.2 will require a recompile of all native add-ons. (The API surface area has not changed significantly, so most add-ons will "just work" after a recompile.)
