Jason Williams

Excited about this, we've been working on the upcoming Container Timing API. Want to learn more? Take a read of the blog post below, put together with @tunetheweb.com and @jdapena.bsky.social. Feedback is very welcome. Try it out and help us shape this API! [This feature is Mozilla Approved]

Had a delightful session today. A great conversation was had w/ @jdapena.bsky.social of @igalia.com about the work being done w/ container timing in Chrome. Both @jason-williams.co.uk + @andydavies.me got mentions. 🙃 This should be published soon. Thx to all who joined in!

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/jsnat.... Register via the badge and watch the stream for FREE! See you on June 11 & 15.

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!

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

The recording of @jason-williams.co.uk talk ‘Temporal: It’s about time!’ is now available to watch online! 2026.stateofthebrowser.com/speaker/jaso... And Temporal has reached Stage 4: www.igalia.com/2026/03/13/T...

good talk from @jason-williams.co.uk at #SotB26 2026.stateofthebrowser.com/speaker/jaso... about Temporal, the thing that will sweep Date.parse() out of our horrified memories and into the dustbin of history (finally, hooray)

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...

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!

@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 🫶

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/contain...

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...

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 ⌚

I built a countdown to State of the Browser using #TemporalAPI codepen.io/CodeRedDigit... Come see @jason-williams.co.uk talk about it

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!

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

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.

Fancy seeing @boajs.dev trending on hacker news! news.ycombinator.com/item?id=4583...

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 👍

Thanks @mmocny.com for the container timing shoutout and stealing my low effort diagram 😂 Great talk @ #perfnow

Boa v0.21 has been released! Plenty of new features, builtins and performance improvements. Blog post with details boajs.dev/blog/2025/10... Discussions: Lobste.rs: lobste.rs/s/upi3xa/boa... news.ycombinator.com/item?id=4567... www.reddit.com/r/rust/comme...

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!

New blog post: I am a Rust compiler engineer looking for a new job nnethercote.github.io/2025/07/18/l...

Hey thanks for the inclusion @infrequently.org, I feel honoured!

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... PR: github.com/helix-editor...

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.

Interop 2025 launched today! Some really exciting features set to become part of Baseline this year.

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

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?...

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

We have released v0.20! This release includes more features, runtime additions, performance optimizations and more. boajs.dev/blog/2024/12... CC @thisweekinrust.bsky.social

Hello World!

In our meeting yesterday, we decided to adopt Element Timing (and the followup Container Timing work) into the working group. CfC coming up!! We also discussed some upcoming improvements to the crash reporting API (still in incubation). Minutes: w3c.github.io/web-performa...

Well that's made my day, jQuery was one of the first open source projects I ever contributed to (~2010!) 👋 @johnresig.com

Thanks to everyone at @perfnow.bsky.social for making us feel welcome and putting on a good conference. Really enjoyed meeting you all!

Crazy refreshing and insightful talk by @jasew.bsky.social & @pcwilliams.bsky.social at #perfNow! This could have continued for another hour only talking about the Container Timing API alone for my taste. Brilliant!

Today @jasew.bsky.social and I tell the story of how our team embedded web technology to give us the best combination of real-time data and rich UI for the #BloombergTerminal. It is an honour to speak at @perfnow.bsky.social. The #PerfNow team have been so welcoming. perfnow.nl/speakers#paulw

The @perfnow.bsky.social conference begins tomorrow in Amsterdam. It is going to be great 👍 For the first time @pcwilliams.bsky.social & @jasew.bsky.social will share the story of how the Bloomberg Terminal uses web tech & what this means for the wider web ecosystem 🎉 If you see us, come say hi 👋

Hello World!