Express@5.1.0: Now the Default on npm with LTS Timeline

Express v5.0.0 was released on September 9th last year, but we didn’t make it the latest release on npm. Many asked us why and when it would be, and frankly we were not ready at the time to take that jump. If you have not followed the news from the project this past year, we have been hard at work reviving the project and when we pushed the initial v5 release there were many loose ends still hanging. So first lets quickly go over some of those loose ends.

Documentation updates

We had not updated the docs, provided migration guides, or even fully reviewed some of the stagnated v4/5 docs in a long time. Since then we have had tons of great contributors help get things into better shape. As with any volunteer based Open Source project, we love contributions to help us improve so as you upgrade please continue to open PRs to fix anything we missed.

You can find our v5 docs and our migration guide on the website.

Migration Support

We know that migrating between versions can be challenging, especially when it involves significant changes in a widely used framework like Express. That’s why we have worked on a solution to simplify part of the process and reduce the impact on developers.

Thanks to the incredible efforts of Sebastian and Filip, we have developed a new codemod package specifically designed to facilitate the transition from Express v4 to v5, as well as future major versions. This package automates many of the necessary code changes, minimizing manual effort and making the upgrade as smooth and efficient as possible.

However, we understand that not all changes can be automated. Some breaking changes, such as the new Path Route Matching syntax, require manual modifications by developers. You can read more about all of the breaking changes which came with v5 in our original release announcement.

For more details on the migration process and how to use the codemod package, check the repository’s README and the migration guide.

Ecosystem compatibility

The Express ecosystem is one of its strongest assets. It goes back to the early days of Node.js and is the backbone that keeps express popular. When it goes 10 years without a major release everything from middleware to documentation needed updates. We wanted to make sure folks had some time to get all of that updated before we had everyone moving over. Particularly we care about our very large beginner user base who may not know the blog post they are reading is not compatible with what they get from npm i express.

We recognize that some friction is inevitable during major upgrades, but thanks to work from ecosystem partners like Kamil from NestJS working to update express before we went latest we will hopefully be ahead of the curve. And as I said above, we always welcome help to make this transition easier for those who follow after you, PRs are the best support you can give.

Long Term Support

We had been discussing how to support v4 now that v5 was out, but we had not defined a clear guideline or expectation, and we had (still don’t have) end user docs on our plans here. While we still have progress to make here, we have a proposed LTS strategy which will be the basis for our forthcoming docs. Input is very welcome on this so we can make sure it is clearly communicated and acceptable to the community.

Additionally since then we have announced a partnership with HeroDevs to help companies who are less capable of updating. More information on how this will work when v4 EOL will come when we get closer to that time.

Support Phases and Going latest

What does it mean to “go latest”? If you are unfamiliar with how npm dist-tags work, the latest tag is what users will get when they run npm install express. This is important because it means it is the “default installed version” and will trigger the transition of nearly 17 million weekly downloads from our current latest v4.21.2 to v5. As we start this transition we want users, companies, and other organizations to know exactly what it means for support. To help with this we have developed an LTS strategy which defines our 3 support phases and set’s target dates for when v4 will enter EOL.

Express major versions will go through three supported phases:

• CURRENT: A new major version is designated as CURRENT upon release. It is available but not the latest version on npm for a minimum of 3 months.
• ACTIVE: After the minimum 3 month period and the TC agrees it is stable and secure, the ACTIVE version is tagged latest on npm for a minimum of 12 months.
• MAINTENANCE: When a new major version becomes ACTIVE, the previous major version enters MAINTENANCE for 12 months.

CURRENT

• New majors will go through a short period of hardening to ensure stability, security, and ecosystem libraries/resources compatibility.
• We will strive to ensure no breaking changes are included, but reserve the right to make security or high priority fixes of breaking nature within this period.
• CURRENT lines will receive all types of active work including: bug fixes, security patches, new features, and deprecation notices.
• Users are recommended to use CURRENT lines and to upgrade as quickly as their risk profile allows

ACTIVE

• ACTIVE lines will receive all types of active work including: bug fixes, security patches, new features, and deprecation notices.
• For users, ACTIVE lines are considered the most stable and well supported version at any given time.

MAINTENANCE

• MAINTENANCE lines will only receive security patches or high priority bug fixes.
• Users are highly encouraged to upgrade to a CURRENT or ACTIVE release.

Proposed Schedule

For the existing release lines, we will set the following phase dates:

As you can see, this means that v5.1.0 being tagged latest indicates that we moved from CURRENT to ACTIVE which starts the clock on EOL for v4 by moving it to MAINTENANCE. We recognize that v4 is a special case having been the only major version for most of the history of Node.js itself. Because of this, we want to remain flexible and also provide a bit longer support. We want to do what is best for the ecosystem, so consider these goals not commitments.

Finally, what changed in v5.1.0

This release primarily focused on tech debt from supporting so many old Node.js versions and other things that stagnated but were not landed before v5.0.0 went out.

Express 5.1.0 Main Changes

• Add support for Uint8Array in res.send()
• Transitioned all remaining dependencies to use ^ ranges instead of locked versions
• Add package.json funding field to highlight our OpenCollective
• Added support for ETag option in res.sendFile()
• Added support for adding multiple links with the same rel with res.links()
• Performance: Use loop for acceptParams

Changelog v5.1.0

Dependencies updated

We also invested time to prepare several releases in the packages that Express depend on. Most of this packages are used by other libraries and framework as individual libraries.

• body-parser@2.2.0
  • Remove legacy node.js support checks for Brotli & AsyncLocalStorage
  • Remove unpipe & destroy
• router@2.2.0
  • Restore debug. Now with the router scope instead of express.
  • Remove legacy node.js support checks for setImmediate
  • Deprecate non-native promise support
  • Remove after, safe-buffer, array-flatten, setprotoypeof, methods, utils-merge
• finalhandler@2.1.0
  • Remove legacy node.js support checks for headersSent, setImmediate, & http2 support
  • Remove unpipe
• serve-static@2.2.0

Thanks and What’s Next

Thanks so much to everyone involved in Express over the past year, the work all our contributors have put in is incredible, and we couldn’t do it without them. If you are not able to become a contributor yourself, please consider asking your companies to support the project financially on OpenCollective.

As we look ahead, we’re excited to keep building momentum. If you haven’t read it yet, our Rewind 2024 + 2025 Vision blog post lays out where we’ve been and where we’re headed. This includes performances scoped packages, better automation, security hardening, and more.

One major initiative is our new Performance Working Group, focused on identifying and fixing long-standing bottlenecks in Express. We’re grateful to be kicking this off with support from the Sovereign Tech Fund (STF), who are helping us invest in long-term sustainability and performance of core infrastructure. Additionally, we will be working to improve our Typescript DX and taking next steps to improve the website.

And yes, v6 discussions are already starting to heat up. Keep an eye out for updates, and as always, see you in the issues!

Big thanks to @wesleytodd, @blakeembrey, @bjohansebas, @UlisesGascon, @Phillip9587, @carpasse, @jonchurch, @ctcpip, @inigomarquinez, @carlosstenzel, @crandmck, @chrisdel101, @dpopp07, @Ayoub-Mabrouk, @jonkoops, @IamLizu, @marco-ippolito, @ipreencekmr, @ShubhamOulkar, @raksbisht, @jeffreybaird, @dougwilson, @mertcanaltin, @GeorgeShvab, @RobinTail, @EvanHahn, @rhodgkins, @cengizcmataraci, @Shantanugupta43, @italojs, @ljharb, @MaoShizhong, @aroyan, @Binilkks, @danielgindi, @papandreou, @jsoref, @bigbigDreamer, @broofa, @CommanderRoot, @andvea, @juanarbol, @agungjati, @alexandercerutti, @pr4j3sh, @hamirmahal, @slagiewka, @Abdel-Monaam-Aouini, @sazk07, @bhavya3024, @joshbuker, @almic, @FDrag0n, @Dmitry-Kondar, @attrid, @kristof-low, @gireeshpunathil, @UzairJ99, @choi2021, @hayden36, @joharkhan99, @peterh-capella, @johnburnett, @nicolasgandrade, @axhuwastaken, @abhijeetpandit7, @peterdanwan, @rehmansheikh222, @corydalis10, @mgsantos177, @wilyJ80, @LuiGeeDev, @juliogarciape, @aelmardhi, @Ahmed1monm, @erensarac, @tomasz13nocon, @tianbuyung, @GreyTearsDev, @aastha-cse, @krzysdz, @Miguelrom, @bnoordhuis, @MehfoozurRehman, @EasonLin0716, @grjan7, @mishrasur7, @gregfenton, @zareefhasan, @Tejas150, @jpricardo, @nikeee, @dotnetCarpenter, @engpetermwangi, @msimerson, @fetsorn, @manoharreddyporeddy, @lancatlin, @mifi, @meowingwhitey, @sheplu, @krsriq, @ravibisht, @wojtekmaj, @aqeelat, @melikhov-dev, @alexstrat, @isnifer, @TorstenDittmann, @Uzlopak, @gurgunday, @kurtextrem, @hdtmccallie, @proudparrot2, @bewinsnw, @jonboulle, @alexander-akait, @alxndrsn, @DimitriPapadopoulos, @greggman, @jkbach, @julien-c, @risu729, @JohnSimumatik, @dhouck, @pedro-php, @aminerol, @robertsky, @ipetrouchtchak-fi, @tinhochu, @Lord-Kamina, @joshkel, @raiandexter0607, @NateEag, @rmhaiderali, @ljeda