Jon Kuperman

Barely had that bike for three weeks. Dang it London.

having react advanced fomo but I've been 🤒

Washing all my mugs so I had to dig deep in the back catalog 😂

Sourcemapped now uses maplint to lint your sourcemaps! github.com/jkup/sourcem...

couple of updates to maplint so it can now be used programmatically to validate sourcemaps! thanks to @jonkuperman.com

This was fun! Sourcemapped: Check the source maps you ship github.com/jkup/sourcem...

Woke up. Checked my watch. 7:30. Got up, shaved and showered. Got dressed. Took out my phone to find my train and realized my watch is still on SF time, where it’s 7:30pm. It’s 3:30am in London 😭

I got the seat on the plane next to the worlds loudest snorer 😭

I had such a lovely week in SF but I am excited to get back home!

I think my hotel is next door to the @cloudflare.social office. Hi friends 👋

sf is too hot. going back

I like when the pilot tells you which runway they are planning to use

I don't have any super popular open source projects but are tools like agentscan.tools not good enough to make them sustainable in this new era?

I’m at Dishoom and a British guy just tried to order a sausage roll

ECMAScript excitement 😉 Congrats to @nicr.dev on advancing `export defer` to Stage 2.7 at @tc39.es today 🎉 It is a performance feature that permits lazy evaluation of re-exported bindings. It is useful for reducing the cost of partially-used barrel files 👍

ECMAScript excitement 😉 Congrats to @ashley-c.bsky.social from TechAtBloomberg on advancing the Composites proposal to Stage 2 at @tc39.es today 🎉 Composites are objects that are compared by value instead of identity. They are an evolution of Record & Tuple proposal.

come work with me! work with dome of the biggest companies on some of the hardest problems! mainmatter.notion.site/Rust-Enginee...

I just did my first non-ebike ride in one and a half years and it was AWFUL

lol why is spotify catching strays in this hn comment news.ycombinator.com/item?id=4964...

I wrote about what I've been up to with my new programming language! Zena targets WebAssembly GC, with a TypeScript-like syntax, sound type system, and lots of cool features like pattern matching, async cancellation, borrow checking, WASI integration, and more! justinfagnani.com/2026/09/09/z...

Have any of you read A Short Stay in Hell? I want to chat about it! www.goodreads.com/en/book/show...

I made this silly sudoku app months ago. Yesterday I looked on Clerk and saw I have ten users who play almost daily. Such a nice feeling. infinitesudoku.com

My neighborhood is so trendy I just ordered a coffee in central London and thought “wow what a deal!”

I like to keep our AI team on their toes by asking about models that don’t exist

Just merged the new experimental `node:bench` module into Node.js main... modeled closely after `node:test`, it adds a basic benchmark runner to core. node --bench benchmark.js

Is slack having a month long outage? slack-status.com

Yes, AI wrote the code. But I have a good understanding of how it works!

whoiz - now on @npmx.dev npmx.dev/package/@jku...

I consider anyone who shows up less than three minutes late a prompt engineer

More and more lately bluesky takes many seconds to load in content. Is this happening to anyone else?

Kind of want to sign up for this aichessathon.com

Porffor alpha is out! It represents a new phase of the project where real-world dependencies are beginning to work and Node compatibility is the main bottleneck. To be clear, it still likely won't work with your app yet, but it is much closer than before. Recap here: honk.foo/porffor-alpha/

This was fun github.com/jkup/whoiz

This was fun github.com/jkup/whoiz

it's happened

github.blog/news-insight...

ECMAScript excitement 😉 Congrats to @yusukesuzuki.bsky.social on shipping TC39 Stage 3 Import Defer in upstream WebKit, heading for Safari 🎉 Import Defer is a performance feature that lets you lazily execute a module on first access to the module namespace 🔥 github.com/WebKit/WebKi...

github and claude down at the same time i guess i'll look out my window for a while

Incredible week at Edinburgh Fringe. Five days, 26 shows. Feeling tired.

Just added Composites* for Stage 2 to the next TC39 agenda. github.com/tc39/proposa... Slides: docs.google.com/presentation... PR: github.com/tc39/agendas... *API name placeholder

Andrew describes the relationship between the version conflict resolution strategies chosen by different package ecosystems and how that determines where costs are incurred.

Do you pronounce it babel or babel?

Don't forget! Tickets are on sale now for @nodeconf.eu The conference is being held in beautiful Bologna, Italy on September 29th and 30th We've got a fantastic agenda, wonderful sponsors, and Italian food. The food alone is worth the trip.

Happy to announce Octane – the successor to Inferno. React’s programming model, compiled. Hooks, Suspense and Actions, compiled ahead of time. No virtual DOM. No Rules of Hooks. No manually maintained dependency arrays. The compiler understands what your code. octanejs.dev

ECMAScript Excitement 🎉 This week, at its 115th meeting, TC39 advanced these proposals: 3️⃣ Await dictionary 2️⃣.7️⃣ Thenable curtailment 2️⃣ Error code property 2️⃣ Fused multiply-add 1️⃣ Intl.DateTimeFormat alignment with other standards 1️⃣ Linear matching 1️⃣ Map.take

dark.ronacher.eu/2026/7/21/ne...

I bought a pack of 6 fancy cookies for the week... that was a mistake

This is such a cool role on one of the greatest teams I've ever worked with. Feel free to message me if you have questions about Bloomberg or their infrastructure org. bloomberg.avature.net/careers/JobD...

Good match.