Jason Williams @jason-williams.co.uk

JavaScript Infrastructure & Tooling @Bloomberg @TC39, creator of Boa (JS Engine)

I will be speaking at #JSNation about Boa: A JavaScript engine in Rust. The Journey, what it taught me and how it works.

Check out my #JSNation badge: gitnation.com/badges/jsnation-2026/jason_williams. Register via the badge and watch the stream for FREE! See you on June 11 & 15.
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Rob Palmer @robpalmer.bsky.social
15d
Container Timing is a new web performance metric to measure when an area of the screen gets painted ⏲️

@jdapena.bsky.social and @jason-williams.co.uk have been working on it for the last couple of years.

It's in Chromium, behind a flag. Hopefully coming to an origin-trial near you soon!
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Thanks all for watching both in person and on the @londonwebstandards.org site! It was a pleasure to present at State Of The Browser 2026 (despite going over time!), hope to be back again next year #sotb
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London Web Standards @londonwebstandards.org
23d
The recording of @jason-williams.co.uk talk ‘Temporal: It’s about time!’ is now available to watch online!
2026.stateofthebrowser.com/speaker/jason-williams/

And Temporal has reached Stage 4: www.igalia.com/2026/03/13/Temporal-Reaches-Stage-4.html
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Stuart Langridge @sil.kryogenix.org
23d
good talk from @jason-williams.co.uk at #SotB26 2026.stateofthebrowser.com/speaker/jason-williams/ about Temporal, the thing that will sweep Date.parse() out of our horrified memories and into the dustbin of history (finally, hooray)
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Temporal is now Stage 4 at TC39 🎂🎂🎂

Thanks to all the other champions of JavaScript's new date-time API. It has been a wild ride over many years!

I wrote a blog post explaining how we got here 📜

bloomberg.github.io/js-blog/post/temporal/
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Wow, was not expecting the mention from my talk to have that much of an effect, sorry @samwho.dev 😂, yes this was from #SotB26, it’s a good resource!
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Oliver Turner @oliverturner.cloud
1mo
@jason-williams.co.uk LOVED the talk, congrats on absolutely smashing it despite the residue of illness 🙌

Hadn’t realised that the Promise method you were referring to was allSettled… thanks so much for delivering my favourite addition 🫶
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Rob Palmer @robpalmer.bsky.social
1mo
Container Timing - a new W3C performance metric - has migrated from Bloomberg to the WICG Github org 🎉

@jason-williams.co.uk made the Bloomberg Terminal use this web metric to measure human-perceived time to start apps. We've found it more useful than existing metrics.

github.com/WICG/container-timing
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robpalmer.bsky.social's profile picture
Rob Palmer @robpalmer.bsky.social
3mo
By many metrics the new Temporal date-time API is the single biggest change to JS ever 🔥

Like Kiesel, V8 chose to reuse Boa's open source Rust-based temporal_rs by @jason-williams.co.uk from TechAtBloomberg, Kevin Ness & Manish 👍

boajs.dev/blog/2025/09/24/temporal-release
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robpalmer.bsky.social's profile picture
Rob Palmer @robpalmer.bsky.social
3mo
State of the Browser 2026 🎉

28th Feb in London 🇬🇧

@jason-williams.co.uk will present "It's about time" discussing the new JavaScript Temporal API ⌚
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Dave Letorey @letorey.co.uk
3mo
I built a countdown to State of the Browser using #TemporalAPI

codepen.io/CodeRedDigital/pen/QwEWxjV?editors=1011

Come see @jason-williams.co.uk talk about it
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Woo! Cannot wait to speak at State Of The Browser 2026. Looking forward to meeting other people in this space too, see you next year!
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Mary Branscombe @marypcbuk.bsky.social
4mo
I've been writing about Temporal (what @b.trl.sn calls 'the fix for our broken date object' which is so bad @samwho.dev made a quiz) for a long time and this time, maybe this time, it's really time for temporal @jason-williams.co.uk tells me, which will make @bkardell.com and many developers happy
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robpalmer.bsky.social's profile picture
Rob Palmer @robpalmer.bsky.social
4mo
ECMAScript excitement 😉

A highly comprehensive article on what will (and might!) land in ES2026 by @marypcbuk.bsky.social 🎉

Includes coverage on Temporal by Boa creator @jason-williams.co.uk who leads the Rust-based temporal_rs library, as used by Google's V8 engine, amongst others.
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Fancy seeing @boajs.dev trending on hacker news! news.ycombinator.com/item?id=45832051
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Rob Palmer @robpalmer.bsky.social
5mo
ECMAScript excitement 😉

Congrats to @manishearth.bsky.social on unflagging TC39 Stage 3 Temporal in V8 today. Heading for Chrome 144 🎉

By many metrics this new date-time API is the single biggest change to JS ever 🔥

V8 uses Boa's temporal_rs by @jason-williams.co.uk Kevin Ness & Manish 👍
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Thanks @mmocny.com for the container timing shoutout and stealing my low effort diagram 😂

Great talk @ #perfnow
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Boa @boajs.dev
6mo
Boa v0.21 has been released! Plenty of new features, builtins and performance improvements.

Blog post with details
boajs.dev/blog/2025/10/22/boa-release-21

Discussions:
Lobste.rs: lobste.rs/s/upi3xa/boa_release_v0_21_new_release_boa

news.ycombinator.com/item?id=45676727

www.reddit.com/r/rust/comments/1odnore/boa_0210_release_a_javascript_engine_written_in
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This is huge, Temporal is on its way, its been a long effort and great to see collaboration on a centralized Rust library including V8 who have never integrated Rust before now! Shout out to everyone who has been involved. Much more info in the blog post!
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Nicholas Nethercote @nnethercote.bsky.social
9mo
New blog post: I am a Rust compiler engineer looking for a new job

nnethercote.github.io/2025/07/18/looking-for-a-new-job.html
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Hey thanks for the inclusion @infrequently.org, I feel honoured!
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I’ve added support for the DAP “startDebugging” request in the Helix Editor. This means you can now debug JavaScript/TypeScript! It has been released in v25.07

helix-editor.com/news/release-25-07-highlights/

PR: github.com/helix-editor/helix/pull/13403
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robpalmer.bsky.social's profile picture
Rob Palmer @robpalmer.bsky.social
10mo
Boa's temporal_js may turn out to be one of the most widely used implementations of the TC39 Stage 3 Temporal API 👍

An independent open source project having impact on the whole JS ecosystem.

The Boa community has come along way since it was started by @jason-williams.co.uk seven years ago.
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Rachel Andrew @rachelandrew.bsky.social
1y
Interop 2025 launched today! Some really exciting features set to become part of Baseline this year.
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I’ve been helping (alongside others) to Champion Temporal for around 6 years now, it’s great to see it approaching the finish line. The responses have been positive.

Great work @joshcena.com and @meyerweb.com on the MDN documentation, momentous effort. Also props to the main man @ptomato.name
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Myself and @pcwilliams.net continue to be humbled by the response we had at @perfnow.bsky.social. Our talk “Bloomberg Becomes Browser” has been published! You can watch it here: youtu.be/y1MCLZm8yAY?si=Ha4325jPw8841-3j
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Fantastic to see @boajs.dev at the top of JS Weekly! Nice snake illustration too.

There’s some good changes in this release and more coming up for 2025.

“This is no toy engine” - javascriptweekly.com/issues/716

CC @cooperx86.bsky.social
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boajs.dev's profile picture
Boa @boajs.dev
1y
We have released v0.20!

This release includes more features, runtime additions, performance optimizations and more.

boajs.dev/blog/2024/12/05/boa-release-020

CC @thisweekinrust.bsky.social
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boajs.dev's profile picture
Boa @boajs.dev
1y
Hello World!
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