Daniel Rosenwasser
@danr.bsky.social
TypeScript Product Manager and TC39 rep working on JavaScript standards.
Enthusiast of compilers, dev tools, language VMs/runtimes.
Enthusiast of compilers, dev tools, language VMs/runtimes.
Reposted by Daniel Rosenwasser
Forgive me, I wrote a thing about AI: journal.stuffwithstuff.com/2026/01/24/t...
The Value of Things – journal.stuffwithstuff.com
journal.stuffwithstuff.com
January 29, 2026 at 12:37 AM
Forgive me, I wrote a thing about AI: journal.stuffwithstuff.com/2026/01/24/t...
Reposted by Daniel Rosenwasser
"Once men turned their thinking over to machines in the hope that this would set them free. But that only permitted other men with machines to enslave them."
― Frank Herbert, Dune
cassidoo.co/post/good-br...
― Frank Herbert, Dune
cassidoo.co/post/good-br...
Do not give up your brain
It's tempting to just let tools think for you, but you still need to be able to think for yourself and stay sharp.
cassidoo.co
January 17, 2026 at 3:32 AM
"Once men turned their thinking over to machines in the hope that this would set them free. But that only permitted other men with machines to enslave them."
― Frank Herbert, Dune
cassidoo.co/post/good-br...
― Frank Herbert, Dune
cassidoo.co/post/good-br...
Reposted by Daniel Rosenwasser
Reposted by Daniel Rosenwasser
You may have noticed that search on the VS Code website has gotten a lot quicker lately.
In our latest blogpost, João Moreno breaks down the engineering process behind docfind, a search engine we built that runs entirely in your browser using WebAssembly: code.visualstudio.com/blogs/2026/0...
In our latest blogpost, João Moreno breaks down the engineering process behind docfind, a search engine we built that runs entirely in your browser using WebAssembly: code.visualstudio.com/blogs/2026/0...
January 15, 2026 at 3:46 PM
You may have noticed that search on the VS Code website has gotten a lot quicker lately.
In our latest blogpost, João Moreno breaks down the engineering process behind docfind, a search engine we built that runs entirely in your browser using WebAssembly: code.visualstudio.com/blogs/2026/0...
In our latest blogpost, João Moreno breaks down the engineering process behind docfind, a search engine we built that runs entirely in your browser using WebAssembly: code.visualstudio.com/blogs/2026/0...
Reposted by Daniel Rosenwasser
wrote some things I've been thinking about ai
... and it ended up feeling very personal
roe.dev/blog/the-go...
... and it ended up feeling very personal
roe.dev/blog/the-go...
The golden thread
AI can serve us as a force multiplier, augmenting our own agency and making the most of our own effort, hard work and value. Not by replacing it.
roe.dev
January 14, 2026 at 11:09 PM
wrote some things I've been thinking about ai
... and it ended up feeling very personal
roe.dev/blog/the-go...
... and it ended up feeling very personal
roe.dev/blog/the-go...
"It was the 90s, everything in Unicode seemed like a good idea."
January 14, 2026 at 10:46 PM
"It was the 90s, everything in Unicode seemed like a good idea."
Fun story from today. I'm currently trying to get `--strict` on by default in TypeScript 6.0.
Our test suite has many tests which are written with `--strict false`, so I am updating them by adding a special comment our test suite recognizes for options
// @strict: false
However...
Our test suite has many tests which are written with `--strict false`, so I am updating them by adding a special comment our test suite recognizes for options
// @strict: false
However...
January 14, 2026 at 10:44 PM
Fun story from today. I'm currently trying to get `--strict` on by default in TypeScript 6.0.
Our test suite has many tests which are written with `--strict false`, so I am updating them by adding a special comment our test suite recognizes for options
// @strict: false
However...
Our test suite has many tests which are written with `--strict false`, so I am updating them by adding a special comment our test suite recognizes for options
// @strict: false
However...
Reposted by Daniel Rosenwasser
My GopherCon talk was just posted!
GopherCon 2025: Porting the TypeScript Compiler to Go for a 10x Speedup V2 - Jake Bailey
YouTube video by Gopher Academy
youtu.be
January 7, 2026 at 2:50 AM
My GopherCon talk was just posted!
Who will be the first to run @googleballs.com in a type system?
January 5, 2026 at 6:36 PM
Who will be the first to run @googleballs.com in a type system?
Reposted by Daniel Rosenwasser
I just switched a project from `typescript` to `@typescript/native-preview` and reduced pnpm build time by 81% 🤯
January 5, 2026 at 3:17 PM
I just switched a project from `typescript` to `@typescript/native-preview` and reduced pnpm build time by 81% 🤯
Reposted by Daniel Rosenwasser
It's the first Monday of 2026! Awful, we know.
But have you tried out TypeScript's native previews, or do you hate when your editor and builds are faster?
But have you tried out TypeScript's native previews, or do you hate when your editor and builds are faster?
January 5, 2026 at 5:46 PM
It's the first Monday of 2026! Awful, we know.
But have you tried out TypeScript's native previews, or do you hate when your editor and builds are faster?
But have you tried out TypeScript's native previews, or do you hate when your editor and builds are faster?
Reposted by Daniel Rosenwasser
🥳 TypeSlayer is out! celebrate by posting what your type graph looks like! it legit has an actual leaderboard now: so bonus points if you win lol 🏆🏆
run: `npx typeslayer`
source: github.com/dimitropoulo...
run: `npx typeslayer`
source: github.com/dimitropoulo...
January 2, 2026 at 2:00 AM
🥳 TypeSlayer is out! celebrate by posting what your type graph looks like! it legit has an actual leaderboard now: so bonus points if you win lol 🏆🏆
run: `npx typeslayer`
source: github.com/dimitropoulo...
run: `npx typeslayer`
source: github.com/dimitropoulo...
Reposted by Daniel Rosenwasser
Your TypeScript year in review
You "silenced" 417 errors with `as any` that turned into runtime errors as soon as the code ran
TypeScript printed 4,693 error messages. 26 of them made sense
You spent 98 minutes waiting for tsc to run. During this time you spent 544 minutes reading social media
You "silenced" 417 errors with `as any` that turned into runtime errors as soon as the code ran
TypeScript printed 4,693 error messages. 26 of them made sense
You spent 98 minutes waiting for tsc to run. During this time you spent 544 minutes reading social media
December 30, 2025 at 1:59 AM
Your TypeScript year in review
You "silenced" 417 errors with `as any` that turned into runtime errors as soon as the code ran
TypeScript printed 4,693 error messages. 26 of them made sense
You spent 98 minutes waiting for tsc to run. During this time you spent 544 minutes reading social media
You "silenced" 417 errors with `as any` that turned into runtime errors as soon as the code ran
TypeScript printed 4,693 error messages. 26 of them made sense
You spent 98 minutes waiting for tsc to run. During this time you spent 544 minutes reading social media
Reposted by Daniel Rosenwasser
👋 Hi! For those unfamiliar I'm Hawk, a UX Engineer on the @vscode.dev team. As 2025 comes to a close, I've been wanting to get a pulse on how folks are writing code.
Genuinely curious: What tool(s) do you use? What do you like/dislike about them? What do you wish your tool could do that it doesn't?
Genuinely curious: What tool(s) do you use? What do you like/dislike about them? What do you wish your tool could do that it doesn't?
December 28, 2025 at 3:43 AM
👋 Hi! For those unfamiliar I'm Hawk, a UX Engineer on the @vscode.dev team. As 2025 comes to a close, I've been wanting to get a pulse on how folks are writing code.
Genuinely curious: What tool(s) do you use? What do you like/dislike about them? What do you wish your tool could do that it doesn't?
Genuinely curious: What tool(s) do you use? What do you like/dislike about them? What do you wish your tool could do that it doesn't?
Reposted by Daniel Rosenwasser
My regular PSA that if you enjoy working on developer tools, then Jane Street is kind of an amazing place. Apply here! There's no special posting, so just apply for the Software Engineering role, and express your interests in dev-tools in a note.
janestreet.com/apply
janestreet.com/apply
December 18, 2025 at 5:31 PM
My regular PSA that if you enjoy working on developer tools, then Jane Street is kind of an amazing place. Apply here! There's no special posting, so just apply for the Software Engineering role, and express your interests in dev-tools in a note.
janestreet.com/apply
janestreet.com/apply
Reposted by Daniel Rosenwasser
TypeScript excitement 😉
The infamous Dimitri is cooking up a slick type analysis tool called TypeSlayer 🔥
"If you have a large enough project, there are performance problems where you can shave 100 seconds off CI by making a 5 line change. The problem is knowing out where to make that change."
The infamous Dimitri is cooking up a slick type analysis tool called TypeSlayer 🔥
"If you have a large enough project, there are performance problems where you can shave 100 seconds off CI by making a 5 line change. The problem is knowing out where to make that change."
⚔️introducing TypeSlayer⚔️ A #typescript type performance benchmarking and analysis tool. A summation of everything learned from the benchmarking required to make the Doom project happen.
It's got MCP support, Perfetto, Speedscope, Treemap, duplicate package detection, and more.
It's got MCP support, Perfetto, Speedscope, Treemap, duplicate package detection, and more.
December 11, 2025 at 5:04 AM
TypeScript excitement 😉
The infamous Dimitri is cooking up a slick type analysis tool called TypeSlayer 🔥
"If you have a large enough project, there are performance problems where you can shave 100 seconds off CI by making a 5 line change. The problem is knowing out where to make that change."
The infamous Dimitri is cooking up a slick type analysis tool called TypeSlayer 🔥
"If you have a large enough project, there are performance problems where you can shave 100 seconds off CI by making a 5 line change. The problem is knowing out where to make that change."
Reposted by Daniel Rosenwasser
now in early-access/alpha/beta/gamma/whatever-you-wanna-call-it.
here's a walkthrough: youtu.be/IP6EZXzXBzY
here's a walkthrough: youtu.be/IP6EZXzXBzY
TypeSlayer - a TypeScript types performance tool
YouTube video by Michigan TypeScript
youtu.be
December 11, 2025 at 3:44 AM
now in early-access/alpha/beta/gamma/whatever-you-wanna-call-it.
here's a walkthrough: youtu.be/IP6EZXzXBzY
here's a walkthrough: youtu.be/IP6EZXzXBzY
Reposted by Daniel Rosenwasser
⚔️introducing TypeSlayer⚔️ A #typescript type performance benchmarking and analysis tool. A summation of everything learned from the benchmarking required to make the Doom project happen.
It's got MCP support, Perfetto, Speedscope, Treemap, duplicate package detection, and more.
It's got MCP support, Perfetto, Speedscope, Treemap, duplicate package detection, and more.
December 11, 2025 at 3:44 AM
⚔️introducing TypeSlayer⚔️ A #typescript type performance benchmarking and analysis tool. A summation of everything learned from the benchmarking required to make the Doom project happen.
It's got MCP support, Perfetto, Speedscope, Treemap, duplicate package detection, and more.
It's got MCP support, Perfetto, Speedscope, Treemap, duplicate package detection, and more.
Reposted by Daniel Rosenwasser
It’s amazing how quickly the Go version of TypeScript was created. The key “trick” of the TS team was to port, not to rewrite: 2ality.com/2025/03/type...
December 2, 2025 at 11:53 PM
It’s amazing how quickly the Go version of TypeScript was created. The key “trick” of the TS team was to port, not to rewrite: 2ality.com/2025/03/type...
Reposted by Daniel Rosenwasser
It’s good! My main task right now at Vanta (when not wrangling organizational growth stuff) is migrating all of our packages to it, even the ones doing crazy shenanigans that tsgo catches and tsc incorrectly let pass. (There are only a handful in our millions of lines of code.)
I repeat: it’s good!
I repeat: it’s good!
I'm sure many of you have already been trying out the native preview, but if you haven't, now is the best time to start!
We've got some updates on TypeScript 7! The new native port
- can type-check any project
- supports --build and --incremental
- has rich editor features implemented
- is still 10x faster
and is ready for you to try today!
devblogs.microsoft.com/typescript/p...
- can type-check any project
- supports --build and --incremental
- has rich editor features implemented
- is still 10x faster
and is ready for you to try today!
devblogs.microsoft.com/typescript/p...
December 2, 2025 at 7:57 PM
It’s good! My main task right now at Vanta (when not wrangling organizational growth stuff) is migrating all of our packages to it, even the ones doing crazy shenanigans that tsgo catches and tsc incorrectly let pass. (There are only a handful in our millions of lines of code.)
I repeat: it’s good!
I repeat: it’s good!
Reposted by Daniel Rosenwasser
TypeScript excitement 😉
News on the Go-based TS 7.0 🎉
🔷 Checker is very compatible with TS 5.9
🔷 Language Server maturity leapt forward
🔷 JS downlevel is limited: ES2021 now, ES2015 in future
🔷 JS checking gets stricter
🔷 No API access yet
News on the Go-based TS 7.0 🎉
🔷 Checker is very compatible with TS 5.9
🔷 Language Server maturity leapt forward
🔷 JS downlevel is limited: ES2021 now, ES2015 in future
🔷 JS checking gets stricter
🔷 No API access yet
We've got some updates on TypeScript 7! The new native port
- can type-check any project
- supports --build and --incremental
- has rich editor features implemented
- is still 10x faster
and is ready for you to try today!
devblogs.microsoft.com/typescript/p...
- can type-check any project
- supports --build and --incremental
- has rich editor features implemented
- is still 10x faster
and is ready for you to try today!
devblogs.microsoft.com/typescript/p...
Progress on TypeScript 7 - December 2025 - TypeScript
Earlier this year, the TypeScript team announced that we’ve been porting the compiler and language service to native code to take advantage of better raw performance, memory usage, and parallelism. Th...
devblogs.microsoft.com
December 2, 2025 at 6:02 PM
TypeScript excitement 😉
News on the Go-based TS 7.0 🎉
🔷 Checker is very compatible with TS 5.9
🔷 Language Server maturity leapt forward
🔷 JS downlevel is limited: ES2021 now, ES2015 in future
🔷 JS checking gets stricter
🔷 No API access yet
News on the Go-based TS 7.0 🎉
🔷 Checker is very compatible with TS 5.9
🔷 Language Server maturity leapt forward
🔷 JS downlevel is limited: ES2021 now, ES2015 in future
🔷 JS checking gets stricter
🔷 No API access yet
Reposted by Daniel Rosenwasser
I'm sure many of you have already been trying out the native preview, but if you haven't, now is the best time to start!
We've got some updates on TypeScript 7! The new native port
- can type-check any project
- supports --build and --incremental
- has rich editor features implemented
- is still 10x faster
and is ready for you to try today!
devblogs.microsoft.com/typescript/p...
- can type-check any project
- supports --build and --incremental
- has rich editor features implemented
- is still 10x faster
and is ready for you to try today!
devblogs.microsoft.com/typescript/p...
Progress on TypeScript 7 - December 2025 - TypeScript
Earlier this year, the TypeScript team announced that we’ve been porting the compiler and language service to native code to take advantage of better raw performance, memory usage, and parallelism. Th...
devblogs.microsoft.com
December 2, 2025 at 5:58 PM
I'm sure many of you have already been trying out the native preview, but if you haven't, now is the best time to start!
Reposted by Daniel Rosenwasser
A status update on the TypeScript rewrite
TL;DR - if you haven't tried it already, you should!
TL;DR - if you haven't tried it already, you should!
Progress on TypeScript 7 - December 2025 - TypeScript
Earlier this year, the TypeScript team announced that we’ve been porting the compiler and language service to native code to take advantage of better raw performance, memory usage, and parallelism. Th...
devblogs.microsoft.com
December 2, 2025 at 5:37 PM
A status update on the TypeScript rewrite
TL;DR - if you haven't tried it already, you should!
TL;DR - if you haven't tried it already, you should!
Reposted by Daniel Rosenwasser
We've got some updates on TypeScript 7! The new native port
- can type-check any project
- supports --build and --incremental
- has rich editor features implemented
- is still 10x faster
and is ready for you to try today!
devblogs.microsoft.com/typescript/p...
- can type-check any project
- supports --build and --incremental
- has rich editor features implemented
- is still 10x faster
and is ready for you to try today!
devblogs.microsoft.com/typescript/p...
Progress on TypeScript 7 - December 2025 - TypeScript
Earlier this year, the TypeScript team announced that we’ve been porting the compiler and language service to native code to take advantage of better raw performance, memory usage, and parallelism. Th...
devblogs.microsoft.com
December 2, 2025 at 5:48 PM
We've got some updates on TypeScript 7! The new native port
- can type-check any project
- supports --build and --incremental
- has rich editor features implemented
- is still 10x faster
and is ready for you to try today!
devblogs.microsoft.com/typescript/p...
- can type-check any project
- supports --build and --incremental
- has rich editor features implemented
- is still 10x faster
and is ready for you to try today!
devblogs.microsoft.com/typescript/p...