Yoav Weiss
@yoav.ws
On a mission to make the web faster, one perf feature at a time. Web platform @ Shopify. WebPerfWG and WICG co-chair. RICG4life. Opinions are my own, etc.
Reposted by Yoav Weiss
Out-of-order HTML patching, another proposal from TPAC, lets HTML be presented non-linearly, and a single file can update multiple parts of the page.
Would this feature be useful to you?
Would this feature be useful to you?
November 19, 2025 at 4:10 PM
Out-of-order HTML patching, another proposal from TPAC, lets HTML be presented non-linearly, and a single file can update multiple parts of the page.
Would this feature be useful to you?
Would this feature be useful to you?
Compression dictionaries is now an official RFC! www.rfc-editor.org/rfc/rfc9842....
RFC 9842: Compression Dictionary Transport
This document specifies a mechanism for dictionary-based compression in the
Hypertext Transfer Protocol (HTTP). By utilizing this technique, clients and
servers can reduce the size of transmitted data...
www.rfc-editor.org
October 1, 2025 at 5:56 AM
Compression dictionaries is now an official RFC! www.rfc-editor.org/rfc/rfc9842....
Reposted by Yoav Weiss
I'm proposing a change to iframes that will allow child frames synchronous access to data attributes on the parent frame. Let me know your thoughts: github.com/blittle/ifra...
GitHub - blittle/iframe-data-attributes: Iframe Data Initialization Attributes
Iframe Data Initialization Attributes. Contribute to blittle/iframe-data-attributes development by creating an account on GitHub.
github.com
September 30, 2025 at 3:40 PM
I'm proposing a change to iframes that will allow child frames synchronous access to data attributes on the parent frame. Let me know your thoughts: github.com/blittle/ifra...
Reposted by Yoav Weiss
✨ SPDY STREAM 011 ✨ w/ @krzksz.bsky.social & @yoav.ws
After deploying the SPECULATION RULES API to their merchants, they join me this week to discuss the experience and their findings. Join us! (updated day and time)
📆 Thursday Sept 25
⏰ 11am EST, 5pm CEST
🔗 bit.ly/spdy-stream-011
After deploying the SPECULATION RULES API to their merchants, they join me this week to discuss the experience and their findings. Join us! (updated day and time)
📆 Thursday Sept 25
⏰ 11am EST, 5pm CEST
🔗 bit.ly/spdy-stream-011
September 22, 2025 at 8:25 PM
✨ SPDY STREAM 011 ✨ w/ @krzksz.bsky.social & @yoav.ws
After deploying the SPECULATION RULES API to their merchants, they join me this week to discuss the experience and their findings. Join us! (updated day and time)
📆 Thursday Sept 25
⏰ 11am EST, 5pm CEST
🔗 bit.ly/spdy-stream-011
After deploying the SPECULATION RULES API to their merchants, they join me this week to discuss the experience and their findings. Join us! (updated day and time)
📆 Thursday Sept 25
⏰ 11am EST, 5pm CEST
🔗 bit.ly/spdy-stream-011
@lukewarlow.dev I just discovered github.com/whatwg/fetch... thanks to @jakearchibald.com
Something like this has been a recurring request at the WebPerfWG, beyond `fetch()` github.com/w3c/resource...
It'd be great if this could cover both!
Something like this has been a recurring request at the WebPerfWG, beyond `fetch()` github.com/w3c/resource...
It'd be great if this could cover both!
WIP: Add a mechanism to fetch to track progress by lukewarlow · Pull Request #1843 · whatwg/fetch
This is not ready for review this is WIP.
At least two implementers are interested (and none opposed):
…
…
Tests are written and can be reviewed and commented upon at:
…
Implementation b...
github.com
September 16, 2025 at 4:35 AM
@lukewarlow.dev I just discovered github.com/whatwg/fetch... thanks to @jakearchibald.com
Something like this has been a recurring request at the WebPerfWG, beyond `fetch()` github.com/w3c/resource...
It'd be great if this could cover both!
Something like this has been a recurring request at the WebPerfWG, beyond `fetch()` github.com/w3c/resource...
It'd be great if this could cover both!
Reposted by Yoav Weiss
📝 Fetch streams are great, but contrary to popular belief, they're not good for measuring upload/downloading progress.
⬇️ Here's why, and how to avoid the gotchas ⬇️
jakearchibald.com/2025/fetch-s...
⬇️ Here's why, and how to avoid the gotchas ⬇️
jakearchibald.com/2025/fetch-s...
Fetch streams are great, but not for measuring upload/downloading progress
They're inaccurate, and there are better ways.
jakearchibald.com
September 15, 2025 at 3:37 PM
📝 Fetch streams are great, but contrary to popular belief, they're not good for measuring upload/downloading progress.
⬇️ Here's why, and how to avoid the gotchas ⬇️
jakearchibald.com/2025/fetch-s...
⬇️ Here's why, and how to avoid the gotchas ⬇️
jakearchibald.com/2025/fetch-s...
Reposted by Yoav Weiss
Great post and it's been a pleasure helping @krzksz.bsky.social and @yoav.ws get this working on Shopify.
performance.shopify.com/blogs/blog/s...
performance.shopify.com/blogs/blog/s...
Speculation Rules at Shopify
We all love quick and snappy online shopping experiences. Fast navigations from one product page to the next reduce friction and allow people to find all the products they want in that store. To achie...
performance.shopify.com
August 29, 2025 at 3:57 PM
Great post and it's been a pleasure helping @krzksz.bsky.social and @yoav.ws get this working on Shopify.
performance.shopify.com/blogs/blog/s...
performance.shopify.com/blogs/blog/s...
Reposted by Yoav Weiss
Starting my new role on Monday. Could be anywhere.
July 31, 2025 at 12:57 PM
Starting my new role on Monday. Could be anywhere.
Reposted by Yoav Weiss
today is my 40th birthday. to toot my own horn a bit, I'm the happiest, healthiest, and most successful I've ever been, so I'm going to indulge myself and do one of those "40 things that made me who I am" threads
so buckle up (or mute me for the next little bit 😆)
so buckle up (or mute me for the next little bit 😆)
June 27, 2025 at 12:25 AM
today is my 40th birthday. to toot my own horn a bit, I'm the happiest, healthiest, and most successful I've ever been, so I'm going to indulge myself and do one of those "40 things that made me who I am" threads
so buckle up (or mute me for the next little bit 😆)
so buckle up (or mute me for the next little bit 😆)
Reposted by Yoav Weiss
Blink: Intent to Implement and Ship: Http cookie prefix
Blink: Intent to Implement and Ship: Http cookie prefix
Blink: Intent to Implement and Ship: Http cookie prefix
groups.google.com
June 19, 2025 at 2:01 PM
Blink: Intent to Implement and Ship: Http cookie prefix
Reposted by Yoav Weiss
CSS uses a complex algorithm to decide how to animate transforms. If you get it wrong, as many folks do, you end up with an unnatural animation.
Here's how it works, and how to avoid the pitfalls.
jakearchibald.com/2025/animati...
Here's how it works, and how to avoid the pitfalls.
jakearchibald.com/2025/animati...
Animating zooming using CSS: transform order is important… sometimes
How to get the right transform animation.
jakearchibald.com
June 17, 2025 at 11:20 AM
CSS uses a complex algorithm to decide how to animate transforms. If you get it wrong, as many folks do, you end up with an unnatural animation.
Here's how it works, and how to avoid the pitfalls.
jakearchibald.com/2025/animati...
Here's how it works, and how to avoid the pitfalls.
jakearchibald.com/2025/animati...
In case anyone out there is looking for a good-first Chromium bug, issues.chromium.org/issues/42421... is one I'd be happy to mentor someone through..
Chromium
issues.chromium.org
June 12, 2025 at 7:53 AM
In case anyone out there is looking for a good-first Chromium bug, issues.chromium.org/issues/42421... is one I'd be happy to mentor someone through..
What do y'all think of reviving <img lowsrc>? (as a data URI, used until the real image loads)
June 9, 2025 at 3:43 PM
What do y'all think of reviving <img lowsrc>? (as a data URI, used until the real image loads)
Reposted by Yoav Weiss
Great video!
Hoping my “Bug Fixes” PR mentioned at 24:20 can make it into WebKit soon 😊
Hoping my “Bug Fixes” PR mentioned at 24:20 can make it into WebKit soon 😊
✨ How We Contribute To Browser Standards ✨ by @yoav.ws
The 3rd of the presentations from the #SPDYmeetup 003.
🔸 Yoav shares how his career working on browsers and for browser vendors has now brought him to Shopify, enabling him to address possible shortcomings in standards
🎥 youtu.be/VEYxyNxfqG8
The 3rd of the presentations from the #SPDYmeetup 003.
🔸 Yoav shares how his career working on browsers and for browser vendors has now brought him to Shopify, enabling him to address possible shortcomings in standards
🎥 youtu.be/VEYxyNxfqG8
June 4, 2025 at 11:29 PM
Great video!
Hoping my “Bug Fixes” PR mentioned at 24:20 can make it into WebKit soon 😊
Hoping my “Bug Fixes” PR mentioned at 24:20 can make it into WebKit soon 😊
Reposted by Yoav Weiss
✨ How We Contribute To Browser Standards ✨ by @yoav.ws
The 3rd of the presentations from the #SPDYmeetup 003.
🔸 Yoav shares how his career working on browsers and for browser vendors has now brought him to Shopify, enabling him to address possible shortcomings in standards
🎥 youtu.be/VEYxyNxfqG8
The 3rd of the presentations from the #SPDYmeetup 003.
🔸 Yoav shares how his career working on browsers and for browser vendors has now brought him to Shopify, enabling him to address possible shortcomings in standards
🎥 youtu.be/VEYxyNxfqG8
June 4, 2025 at 11:10 AM
✨ How We Contribute To Browser Standards ✨ by @yoav.ws
The 3rd of the presentations from the #SPDYmeetup 003.
🔸 Yoav shares how his career working on browsers and for browser vendors has now brought him to Shopify, enabling him to address possible shortcomings in standards
🎥 youtu.be/VEYxyNxfqG8
The 3rd of the presentations from the #SPDYmeetup 003.
🔸 Yoav shares how his career working on browsers and for browser vendors has now brought him to Shopify, enabling him to address possible shortcomings in standards
🎥 youtu.be/VEYxyNxfqG8
My take on coding LLMs: they have no understanding of concepts and just do pattern matching. But pattern matching goes a looooong way
June 4, 2025 at 6:30 AM
My take on coding LLMs: they have no understanding of concepts and just do pattern matching. But pattern matching goes a looooong way
Reposted by Yoav Weiss
✨ Speculation Rules, and Their Effect on Shopify Stores ✨ by @krzksz.bsky.social
🔸 As part of the Growth Services team, Mateusz talks about the team's long journey to implement Speculation Rules at Shopify and, the lessons learned along the way. #SPDYMeetup
🎥 youtu.be/8k2cGNjwJ3c
🔸 As part of the Growth Services team, Mateusz talks about the team's long journey to implement Speculation Rules at Shopify and, the lessons learned along the way. #SPDYMeetup
🎥 youtu.be/8k2cGNjwJ3c
SPECULATION RULES AND THEIR EFFECT ON SHOPIFY STORES by MATEUSZ KRZESZOWIAK
YouTube video by Henri Helvetica
youtu.be
June 3, 2025 at 12:31 PM
✨ Speculation Rules, and Their Effect on Shopify Stores ✨ by @krzksz.bsky.social
🔸 As part of the Growth Services team, Mateusz talks about the team's long journey to implement Speculation Rules at Shopify and, the lessons learned along the way. #SPDYMeetup
🎥 youtu.be/8k2cGNjwJ3c
🔸 As part of the Growth Services team, Mateusz talks about the team's long journey to implement Speculation Rules at Shopify and, the lessons learned along the way. #SPDYMeetup
🎥 youtu.be/8k2cGNjwJ3c
Reposted by Yoav Weiss
Avoiding the fomo this year by eagerly being a part of #perfnow in 2025.
Tickets on sale now to help you avoid that fomo too.
perfnow.nl/speakers.html
Tickets on sale now to help you avoid that fomo too.
perfnow.nl/speakers.html
May 30, 2025 at 10:10 AM
Avoiding the fomo this year by eagerly being a part of #perfnow in 2025.
Tickets on sale now to help you avoid that fomo too.
perfnow.nl/speakers.html
Tickets on sale now to help you avoid that fomo too.
perfnow.nl/speakers.html
Reposted by Yoav Weiss
Forget the G7 ❌, this was the SPDY6 ✅: 🇵🇱🇺🇸🇪🇸🇨🇦🇬🇧🇫🇷.
An assemblage of great global minds for last night's #SPDYmeetup in Toronto. Everything was as stellar as could be. @guaca.bsky.social @yoav.ws + @krzksz.bsky.social all delivered poigant presentations! 🏁 Recordings to be shared shortly. ✨🙏🏾✨
An assemblage of great global minds for last night's #SPDYmeetup in Toronto. Everything was as stellar as could be. @guaca.bsky.social @yoav.ws + @krzksz.bsky.social all delivered poigant presentations! 🏁 Recordings to be shared shortly. ✨🙏🏾✨
May 29, 2025 at 7:35 PM
Forget the G7 ❌, this was the SPDY6 ✅: 🇵🇱🇺🇸🇪🇸🇨🇦🇬🇧🇫🇷.
An assemblage of great global minds for last night's #SPDYmeetup in Toronto. Everything was as stellar as could be. @guaca.bsky.social @yoav.ws + @krzksz.bsky.social all delivered poigant presentations! 🏁 Recordings to be shared shortly. ✨🙏🏾✨
An assemblage of great global minds for last night's #SPDYmeetup in Toronto. Everything was as stellar as could be. @guaca.bsky.social @yoav.ws + @krzksz.bsky.social all delivered poigant presentations! 🏁 Recordings to be shared shortly. ✨🙏🏾✨
Import maps are a great way to minimize cache invalidation in your module tree. But up until recently, they had a ton of sharp edges. So we fixed them!!
shopify.engineering/resilient-im...
shopify.engineering/resilient-im...
Resilient Import Maps - Better Theme Development and Beyond (2025) - Shopify
Import maps are great for both performance and developer experience, but their original limitations made them hard to use, especially at Shopify’s scale. We stepped up and pushed changes across the HT...
shopify.engineering
May 29, 2025 at 12:58 PM
Import maps are a great way to minimize cache invalidation in your module tree. But up until recently, they had a ton of sharp edges. So we fixed them!!
shopify.engineering/resilient-im...
shopify.engineering/resilient-im...
@zachleat.com here's that blog post I promised shopify.engineering/resilient-im...
Resilient Import Maps - Better Theme Development and Beyond (2025) - Shopify
Import maps are great for both performance and developer experience, but their original limitations made them hard to use, especially at Shopify’s scale. We stepped up and pushed changes across the HT...
shopify.engineering
May 29, 2025 at 12:54 PM
@zachleat.com here's that blog post I promised shopify.engineering/resilient-im...
Reposted by Yoav Weiss
Would web devs use this?
- subscribe to highly anticipated features (like Temporal)
- get notified when they land in a new browser / become Baseline
- via email, bsky, GitHub, Slack, whatever
- subscribe to highly anticipated features (like Temporal)
- get notified when they land in a new browser / become Baseline
- via email, bsky, GitHub, Slack, whatever
💡 Idea: a way to get notified when a feature you're interested in ships in a browser (or all of them) so you can start jamming on it immediately
May 28, 2025 at 6:59 PM
Would web devs use this?
- subscribe to highly anticipated features (like Temporal)
- get notified when they land in a new browser / become Baseline
- via email, bsky, GitHub, Slack, whatever
- subscribe to highly anticipated features (like Temporal)
- get notified when they land in a new browser / become Baseline
- via email, bsky, GitHub, Slack, whatever
Reposted by Yoav Weiss
📢 We Announced speakers for the TORONTO SPDY MEETUP 003: Performance At Shopify:
Estela Franco 🇪🇸, Yoav Weiss 🇫🇷 and Mateusz Krzeszowiak 🇵🇱 will walk us through how Shopify is doing their part is helping merchants be fast, and STAY fast.
🎟️ JOIN US bit.ly/spdy_toronto_003
Estela Franco 🇪🇸, Yoav Weiss 🇫🇷 and Mateusz Krzeszowiak 🇵🇱 will walk us through how Shopify is doing their part is helping merchants be fast, and STAY fast.
🎟️ JOIN US bit.ly/spdy_toronto_003
May 19, 2025 at 3:45 PM
📢 We Announced speakers for the TORONTO SPDY MEETUP 003: Performance At Shopify:
Estela Franco 🇪🇸, Yoav Weiss 🇫🇷 and Mateusz Krzeszowiak 🇵🇱 will walk us through how Shopify is doing their part is helping merchants be fast, and STAY fast.
🎟️ JOIN US bit.ly/spdy_toronto_003
Estela Franco 🇪🇸, Yoav Weiss 🇫🇷 and Mateusz Krzeszowiak 🇵🇱 will walk us through how Shopify is doing their part is helping merchants be fast, and STAY fast.
🎟️ JOIN US bit.ly/spdy_toronto_003
Reposted by Yoav Weiss
Latest Chrome (and Safari I think?) implement multiple import maps, which I think enables this behavior (thanks @yoav.ws )
I don’t think you have to do document.write() tricks to get it working, just inline it in html.
I don’t think you have to do document.write() tricks to get it working, just inline it in html.
May 18, 2025 at 4:51 AM
Latest Chrome (and Safari I think?) implement multiple import maps, which I think enables this behavior (thanks @yoav.ws )
I don’t think you have to do document.write() tricks to get it working, just inline it in html.
I don’t think you have to do document.write() tricks to get it working, just inline it in html.
Imagine being a software developer named Claude
May 14, 2025 at 10:56 PM
Imagine being a software developer named Claude