You're Looking at the Wrong Pretext Demo Pretext went viral for its beautiful canvas demos. But the community is showcasing the wrong feature.

Those Pretext demos are stunning, but they're not what's novel or important about this library. What matters is that it can predict the height of any text block without the browser ever touching the DOM!
denodell.com/blog/youre-l...

Performance Engineering in Practice - Den Odell You can prevent most software performance problems if you recognize their predictable patterns. Performance Engineering in Practice introduces author Den Odell’s Fast by Default model that replaces th...

The first reviews of my new book on software performance engineering are coming in:
⭐ "A manifesto against enshittification."
⭐ "The best chapters in this book are worth a whole book."
And now it's 50% off with code "MLOdell" until 26 March:
hubs.la/Q044cvhn0

new MEAP launch, folks ↓

get it half off through march 13th.

Performance Engineering In Practice book cover

🎉 My new book Performance Engineering in Practice is now available through Manning's Early Access Program! 🎉

It's the practical guide to making software fast by default, covering web, backend, mobile, and desktop.

First 5 chapters out now, with a 50% launch discount 🚀
hubs.la/Q044cvhn0

Haha yeah! They needed the constraint to sell something to more than just a few people!

Constraints and the Lost Art of Optimization How working within hard limits produced some of the most elegant software in history, and what we can learn from it.

The first Mac OS fitted in a 64kB ROM. That hard limit didn't hold back innovation, it demanded it.

The engineers who worked within those limits knew their platform completely. We've lost some of that thinking, the knowledge of our foundations.

I wrote more here: denodell.com/blog/constra...

I know! We can do it ourselves with Web Workers, but sounds like something that should be automatic

The Main Thread Is Not Yours Every millisecond your JavaScript runs is a millisecond borrowed from your users. Here's how to be a better guest on the main thread.

The main thread is the only path between your web app and a human being.

When your JavaScript runs too long, the browser stops listening to them. That’s jank.

We’re only borrowing the main thread from users. We should treat it with respect.
denodell.com/blog/the-mai...

Fast by Default After 25 years building sites for global brands, I kept seeing the same pattern appear. A team ships new features, users quietly begin to struggle, and only later do the bug reports start trickling in...

Web Performance Calendar day #4 when @denodell.bsky.social shows us how to adopt a fast-by-default mindset to escape the vicious cycle of ship-complain-panic-patch.

calendar.perfplanet.com/2025/fast-by...

Escape Velocity: Break Free from Framework Gravity After a decade of React dominance, it’s time to remember that frameworks run inside the web, not the other way around.

Frameworks run inside the web, not the other way around.

New post on breaking free from framework gravity, building React apps that respect the platform and could outlast React itself.

denodell.com/blog/escape-...

Appreciate the link to
my post! Thank you!

CSS Weekly Issue #622 Learn everything you need to know about new CSS features released in 2025, useful use cases for obscure media queries, how the corner-shape property works, and more.

CSS Weekly #622

🚀 Best of CSS in 2025
😳 Uncommon media queries
💠 corner-shape property
💬 :heading pseudo-class

Featuring @chriscoyier.net, @dxnny.fun, @jensimmons.bsky.social, @emilkowal.ski, @bram.us, @denodell.bsky.social. @silvestar.codes, @miocene.io. 🙏

cssw.io/issue-622

No trouble at all! In fact it's good, now I can treat it like it's live instead of keep holding back from announcing it. A few more tweaks then I'll do just that! Thank you!

That's great, I'll add that to the list and get some more HTTP Header goodness in there, it's always good with references for those and when to use them...!

That's awesome, thanks for reading my output tag article and finding your way to the new site! I probably should have had the repo private until I was ready to launch, but this gives me more incentive to push on so it's all good! I've been adding more detail to each pattern even today :)

I’d love to know which patterns you’d like to see on there or which ones I have that resonated with you btw? Gives me some focus… Thank you for being my first user!

Oh wow you found that! I’m actively building it right now so some content might be missing, and features come and go. But I’m hoping it’ll end up being really useful once it’s launched properly!

Right!? It’s wild how long it's just been sitting there, waiting to be used. I only stumbled on it when I was debugging a form accessibility issue and craving some better semantics. Turns out HTML had already delivered the goods! 😄

HTML’s Best Kept Secret: The output Tag Make your dynamic content accessible by default with the HTML tag that time forgot.

I recently discovered the HTML tag almost nobody uses.

The <output> tag announces dynamic content to screen readers. Like an ARIA live region, except it's built in.

We've spent years hacking divs when the answer was in the spec. Classic.

New post:
denodell.com/blog/html-be...

Code Reviews That Actually Improve Frontend Quality Most frontend reviews sign off clean code. But your users don’t see the code, they see the bugs you missed.

Frontend code reviews should test the experience, not just the diff.

Too many bugs slip through because no one thought to preview in a browser.
My latest post covers how to shift reviews from “LGTM” to real UX quality checks.

denodell.com/blog/code-re...

We Keep Reinventing CSS, but Styling Was Never the Problem We keep changing how we style the web, but the real problem isn’t CSS. It’s how we build around it.

We keep changing how we style the web.
Tailwind. CSS Modules. CSS-in-JS. Cascade layers.

Still feels off though.

Maybe CSS was never the real problem.

denodell.com/blog/we-keep...

The Web Is About to Get Better for Everyone, Everywhere What happens when accessibility stops being a best practice and starts being the law? We’re about to find out.

The next big shift in frontend isn’t a framework.
It’s a law.

The EU’s accessibility rules will ripple far beyond Europe, and the web will get better because of it.
denodell.com/blog/a-bette...

AI Is Just the Latest Frontend Killer. Don’t Panic. Apparently, frontend developers are about to be made obsolete. This all sounds very familiar.

Apparently, AI just made frontend developers obsolete.
Again.

Don’t panic. I’ve been here before. I know how this goes.
You’ll want to read this one.
denodell.com/blog/ai-is-j...

Building the Web in Islands, Not Mountains Loading spinners. Hydration delays. 300kB for a blog post. There’s a better way to build the web.

Loading spinners. Hydration delays. 300kB of JS for a blog post.
We’ve normalised complexity where it’s not needed.
There’s a better way — and it starts with islands.
denodell.com/blog/buildin...
#frontend #architecture

Hacking Layout Before CSS Even Existed The early web had no layout system. No CSS. So we improvised, slicing, stretching, and nesting our way to structure.

Before CSS, we still had to build layouts.
No grid, no flex, not even float.
Just hacks, slices, and a lot of guesswork.

🆕 Hacking Layout Before CSS Even Existed
What we did, how it worked, and what it still teaches us.

👉 denodell.com/blog/hacking...

Want to Be a Better Frontend Engineer? Try a Week On-Call You’re going to hate me for saying this, but I actually like being on-call. Honestly! It’s taught me more about frontend quality than any bug tracker ever did.

You’re going to hate me for saying this, but I actually like being on-call.
It’s not the 2:43 AM alerts.
It’s what they taught me about frontend quality.

My first piece of new writing in 10 years.
denodell.com/blog/try-a-w...