Andrew Branch

Andrew Branch

@andrewbran.ch

Working on the TypeScript API at Microsoft.

1K followers112 following53 posts

Andrew Branch reposted

Daniel Rosenwasser
@danr.bsky.social

Some speed & memory improvements you'll see with TypeScript 7.1 Beta. We're hoping to land more before RC & stable.

TypeScript@typescriptlang.org

TypeScript 7.1 Beta is now available! Now with a preview API, content mapper support, new features, and some great optimizations. Give it a try and give us some feedback!

devblogs.microsoft.comAnnouncing TypeScript 7.1 Beta - TypeScriptAnnouncing TypeScript 7.1 Beta, bringing a preview API and new features, all while being faster and leaner than TypeScript 7.0.

Andrew Branch reposted

Jiahan Chen
@chenjiahan.bsky.social

Excited that TypeScript will finally support module types based on import attributes! Bundlers and frameworks can now provide accurate types for custom imports:

Andrew Branch reposted

NullVoxPopuli
@nullvoxpopuli.com

Ember now has preliminary TS7 support ~ via the content-mappers feature that merged in TS last week Testers wanted! (requires TS Nightly)

Andrew Branch reposted

Jiahan Chen
@chenjiahan.bsky.social

The TypeScript content mappers PR just merged and is likely to land in 7.1 🎉 This could open a new chapter for everything built on and around TypeScript github.com/microsoft/ty...

github.comContent mappers by andrewbranch · Pull Request #4712 · microsoft/typescript-goImplements microsoft/TypeScript#63800 (comment) Overview Content mappers are external integrations that allow TypeScript to include otherwise unsupported file types in a program. They transform a f...
Andrew Branch
@andrewbran.ch

If you’re not stalking TypeScript PRs, you might be surprised how much you can do with the API in nightlies (and even in 7.0 stable), so here’s a tiny demo that I think hits some of the highlights. 🧵

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Andrew Branch
@andrewbran.ch

Now is a good time to start building with the API and sending feedback my way on GitHub. What are you still missing to be able to move your API-using projects to TS 7?

Andrew Branch
@andrewbran.ch

If you’re not stalking TypeScript PRs, you might be surprised how much you can do with the API in nightlies (and even in 7.0 stable), so here’s a tiny demo that I think hits some of the highlights. 🧵

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Andrew Branch
@andrewbran.ch

This simple example is running in the extension host, but you can imagine passing this connection to your own LSP server, serving additional completions or hovers in TS files by combining its own logic with type checker queries.

Andrew Branch
@andrewbran.ch

This LSP-connected API method is why everything goes through immutable snapshots. You can continue to work with immutable state for as long as you want, even if the user has moved files or continued typing.

Andrew Branch
@andrewbran.ch

If you’re not stalking TypeScript PRs, you might be surprised how much you can do with the API in nightlies (and even in 7.0 stable), so here’s a tiny demo that I think hits some of the highlights. 🧵

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Andrew Branch
@andrewbran.ch

So far, almost all of this code could be mistaken for the old TS 6 API. But under the hood, a lot of care has to go into pretty silly things like making sure when you get the same Type or Symbol twice, they have reference equality. That doesn't come for free anymore.

Andrew Branch
@andrewbran.ch

Let's do something totally different. Here's a VS Code extension, which gets a sidecar API connection to the TypeScript LSP that was already running. All the same APIs are available, and now you can inspect the projects the user has open in their editor. Here we're logging the exports of .ts files.

Andrew Branch
@andrewbran.ch

If you’re not stalking TypeScript PRs, you might be surprised how much you can do with the API in nightlies (and even in 7.0 stable), so here’s a tiny demo that I think hits some of the highlights. 🧵

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Andrew Branch
@andrewbran.ch

Now for some transformation. The new AST is a hybrid of these "remote nodes" backed by binary data and normal JavaScript objects. The client can encode the result into the same binary format so the server can run it through the emitter, in this case. Here's a (dumb) codemod to fix our error.

Andrew Branch
@andrewbran.ch

If you’re not stalking TypeScript PRs, you might be surprised how much you can do with the API in nightlies (and even in 7.0 stable), so here’s a tiny demo that I think hits some of the highlights. 🧵

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Andrew Branch
@andrewbran.ch

Every node materializes into an instance of the same class, all reading the same underlying buffer. The TS types lie and give each node a specialized type. Here, we see `kind` reading its value from an offset computed by the node's index in the flattened AST and the kind field's offset.

Andrew Branch
@andrewbran.ch

To demonstrate the laziness of file decoding, we can see that after recursively visiting one of the two statements in the file, 10 of the 20 nodes were actually materialized. (The timings here look slower than they should because the VFS is not yet production quality.)

Andrew Branch
@andrewbran.ch

If you’re not stalking TypeScript PRs, you might be surprised how much you can do with the API in nightlies (and even in 7.0 stable), so here’s a tiny demo that I think hits some of the highlights. 🧵

View full thread
Andrew Branch
@andrewbran.ch

Slightly more interesting: let's navigate a source file and use the type checker on some stuff. This found the return type 'void' from `console.log` and the return type 'number' from `add`.

Andrew Branch
@andrewbran.ch

But how exactly does that work? The tsgo process encodes the AST in a compact binary format and sends it all over. The client's SourceFile type wraps the Uint8Array and exposes getters for every property you could want to access. Children and other properties are lazily decoded on first access.

Andrew Branch
@andrewbran.ch

If you’re not stalking TypeScript PRs, you might be surprised how much you can do with the API in nightlies (and even in 7.0 stable), so here’s a tiny demo that I think hits some of the highlights. 🧵

Andrew Branch
@andrewbran.ch

The API comes in sync and async flavors. You import from "unstable" for now, but it's not going to change architecturally before 7.1. Breaks will be mostly targeted renames/moves. You access programs through obtaining immutable snapshots. There will be more ways coming soon. More on this later.

Andrew Branch
@andrewbran.ch

Let’s start with something basic like getting diagnostics. Not too much to say about this. Each API call like this is communicating over STDIO with the tsgo process. We'll see some details in a minute.

Andrew Branch reposted

John Reilly
@johnnyreilly.com

If you discount project references (and there's no API support as yet I believe), then all bar around 6 tests of ts-loader are now passing using the 7.1 tsgo TypeScript API! Not quite there yet but significant progress github.com/TypeStrong/t...

github.comSupport TypeScript 7.1 API by Copilot · Pull Request #1704 · TypeStrong/ts-loaderThis PR is an attempt at using the TypeScript 7.1+ API. This pares back the earlier tsgo integration attempt to the new API alone. Instead of carrying both implementations, experimentalNativeApi no...

Andrew Branch reposted

John Reilly
@johnnyreilly.com

Building upon the fine work of @pier.fumagalli.org / @titiancernicova.bsky.social / @andrewbran.ch I've been throwing copilot at the new TypeScript 7.1 API and ts-loader. Very early days but some progress! github.com/TypeStrong/t...

github.comAdd minimal experimental tsgo transpile path by Copilot · Pull Request #1704 · TypeStrong/ts-loaderThis pares back the earlier tsgo integration attempt to the new API alone. Instead of carrying both implementations, experimentalNativeApi now routes through the tsgo API directly, with the existin...

Andrew Branch reposted

mary🐇
@mary.my.id

they coulda trained opus 5 to learn that typescript 7 is stable now because it simply refuses to believe oxlint with type checking enabled only takes 28ms to run

Andrew Branch reposted

Ashley Claymore
@ashley-c.bsky.social

I've been experimenting with having `ts-blank-space` use the (unstable) TypeScript-go JS API. At first it was ~60% slower than using the TS 6 API, but with a bit of investigation, a bug fix, and a small refactor to use different API calls it is now ~24% faster! Draft PR: github.com/bloomberg/ts...

Andrew Branch reposted

TypeScript
@typescriptlang.org

TypeScript 6.0 is now available! This release brings better type-checking for methods, new standard library features, new module features for Node.js, and more! But most important, this release brings us one step closer to the upcoming native-speed 7.0! devblogs.microsoft.com/typescript/a...

devblogs.microsoft.comAnnouncing TypeScript 6.0 - TypeScriptTypeScript 6.0 is now available! TypeScript 6 is a stepping-stone release, aligning with the upcoming native-speed 7.0 release.

Andrew Branch reposted

Joyee Cheung
@joyeecheung.bsky.social

Finished two retrospective blog posts on the journey of require(esm) before 2025 ends: joyeecheung.github.io/blog/2025/12... joyeecheung.github.io/blog/2025/12...

joyeecheung.github.iorequire(esm) in Node.js: from experiment to stabilityMore than a year ago, I set out to revive require(esm) in Node.js and landed an experimental implementation. After a lot of iteration and battle-testing, require(esm) is now unflagged across all suppo

Andrew Branch reposted

TypeScript
@typescriptlang.org

Big news in this year's GitHub Octoverse report: TypeScript is now the most-used language on GitHub! We are thrilled and grateful to see the TypeScript and JavaScript community continue to grow and thrive. 🚀 Read up more at github.blog/news-insight...

github.blogOctoverse: A new developer joins GitHub every second as AI leads TypeScript to #1In this year’s Octoverse, we uncover how AI, agents, and typed languages are driving the biggest shifts in software development in more than a decade.

Andrew Branch reposted

Jake Bailey
@jakebailey.dev

Tonight will be one of the best nightlies of the TypeScript Native Preview ever. 1) @andrewbran.ch fully rewrote the language server infra into a snapshot model. No more data races. It's so cool 2) Sheetal added build mode (-b), and it's even _concurrent_ build mode. 10x+ on dt-tools, hot and cold

Andrew Branch reposted

Jake Bailey
@jakebailey.dev

Next week is gonna be a fun week Soon the scourge of baseUrl, paths, and typesRoot will be purged, replaced with "how about we actually use node_modules like everyone else" (thank you Andrew and Nathan for your efforts, and of course @zkochan.bsky.social and contributors for pnpm)

Andrew Branch reposted

TypeScript
@typescriptlang.org

We just released TypeScript 5.2 Beta! Check out - 'using' Declarations - Decorator Metadata - Easier Tuple Type Notation - Inline Variable Refactoring - Comma Completions in Objects and more! Try it today!

devblogs.microsoft.comAnnouncing TypeScript 5.2 Beta - TypeScriptToday we are excited to announce the availability of TypeScript 5.2 Beta. To get started using the beta, you can get it through NuGet, or through npm with the following command: npm install -D typescr...

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