Microsoft announcing TypeScript 6.0 RC

Today we are excited to announce the Release Candidate (RC) of TypeScript 6.0! To get started using the RC, you can get it through npm with the following command:

npm install -D typescript@

TypeScript 6.0 is a unique release in that we intend for it to be the last release based on the current JavaScript codebase. As announced last year (with recent updates here), we are working on a new codebase for the TypeScript compiler and language service written in Go that takes advantage of the speed of native code and shared-memory multi-threading. This new codebase will be the foundation of TypeScript 7.0 and beyond. TypeScript 6.0 will be the immediate precursor to that release, and in many ways it will act as the bridge between TypeScript 5.9 and 7.0. As such, most changes in TypeScript 6.0 are meant to help align and prepare for adopting TypeScript 7.0.

With that said, there are some new features and improvements that are not just about alignment. Let’s take a look at some of the highlights of this release, followed by a more detailed look at what’s changing for 7.0 and how to prepare for it.

What’s New Since the Beta?​

Since TypeScript 6.0 beta, we have made a few noteworthy changes – mostly to align with the behavior of TypeScript 7.0.

One adjustment is in type-checking for function expressions in generic calls, especially those occurring in generic JSX expressions (see this pull request). This will typically catch more bugs in existing code, though you may find that some generic calls may need an explicit type argument.

We have also extended our deprecation of import assertion syntax (i.e. import ... assert {...}) to import() calls like import(..., { assert: {...}})

Finally, we have updated the DOM types to reflect the latest web standards, including some adjustments to the Temporal APIs as well.

Preparing for TypeScript 7.0​

TypeScript 6.0 is designed as a transition release. While options deprecated in TypeScript 6.0 will continue to work without errors when "ignoreDeprecations": "6.0" is set, those options will be removed entirely in TypeScript 7.0 (the native TypeScript port). If you’re seeing deprecation warnings after upgrading to TypeScript 6.0, we strongly recommend addressing them before adopting TypeScript 7.0 (or trying native previews) in your project.

As for the schedule, we expect TypeScript 7.0 to follow soon after TypeScript 6.0. This should help us maintain continuity while giving us a faster feedback loop for migration issues discovered during adoption.

What’s Next?​

At this point, TypeScript 6.0 is feature-complete, and we anticipate very few changes apart from critical bug fixes to the compiler. Over the next few weeks, we’ll focus on addressing issues reported on the 6.0 branch, so we encourage you to try the RC and share feedback.

We also publish nightly builds on npm and in Visual Studio Code, which can provide a faster snapshot of recently fixed issues.

We are also continuing to work on TypeScript 7.0, and we publish nightly builds of our native previews along with a VS Code extension too. Feedback on both 6.0 and 7.0 are very much appreciated, and we encourage you to try out both if you can.

So give TypeScript 6.0 RC a try in your project, and let us know what you think!

Happy Hacking!

– Daniel Rosenwasser and the TypeScript Team