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Announcing Vitest 4.0 Vitest 4.0 Release Announcement

Vitest 4 is out!

- Browser Mode is Stable
- Visual Regression Testing
- Improved Debugging
- Pool Stabilization
- New APIs
- Bug Fixes

Stay updated with our blog post:

vitest.dev/blog/vitest-4

⚓ Oxlint now supports plugins written in JavaScript ⚓

Developers can customize and extend Oxlint using JavaScript, but at a speed approaching Rust, due to 'raw transfer' between Rust and JS, and other breakthroughs

Many ESLint plugins can run without any modification.

Read the full post👇

ECMAScript excitement 😉

Congrats to proposal champion Dan Minor @mozilla.org on shipping the TC39 Stage 3 Upsert proposal in Firefox 144 🎉

let map = new Map();
map.getOrInsert(key, defaultVal);

It lets you set a default value on a map key without overwriting an existing value 👍

inherit() is going to be absolutely huge for working with CSS custom properties. Two big things it'll enable:

Nested indentation:

--indent: calc(inherit(--indent, 0) + 1);

Overridable design token defaults:

--primary-color: inherit(--primary-color, blue);

Just tried the latest beta and, compared with beta 32, bundling our ArcGIS Maps SDK goes from 5s to 4s 🚀 And watch mode is also working well on Mac. Let’s go!!!

React 19.2 – React The library for web and native user interfaces

React 19.2 is now available!

This release includes Activity, useEffectEvent, React Performance Tracks, partial pre-rendering, and more:

react.dev/blog/2025/10...

I'm very excited to announce the release of the #WebComponents CLI validator! Now you can validate your web components in your build pipelines.

#html #javascript

Huge! Together with screenshot assertions and other things I’ve seen you cooking, it’s shaping up to be an epic release!

Vitest Next generation testing framework powered by Vite

Next version of Browser Mode now also support playwright's trace viewer natively. Just pass down `--browser.trace=on`: main.vitest.dev/guide/browse...

Specification, speed and (a) schedule 356, 11.16 and a future 0.1.0 ?

New post on big general type-checker improvements. How `specification.md` can be used to test both features and performance. And perhaps what is up for version 0.1.0...

Quiet UI A UI library for the Web with a focus on accessibility, longevity, performance, and simplicity.

So much for a soft launch…the cat's out of the bag. I just hope it doesn't get my mascot. 😅

quietui.org 🐭

Built from scratch, I've released my personal creative outlet under a source-available license for folks to use and learn from.

I’d love to hear what you think!

Whimsical Animations Learn how to create charming interactions and delightful touches using the magic of CSS, JavaScript, SVG, and Canvas. I’m sharing all my tricks in this one!

We’re live!! My brand-new course, “Whimsical Animations”, is now available. 🥳🎉

whimsy.joshwcomeau.com

I’m so excited to share all of my animation tools and techniques with y’all. 😄

Enable `noUncheckedSideEffectImports` by default by RyanCavanaugh · Pull Request #62443 · microsoft/TypeScript #62442 doesn't seem to be going well Fixes #62421

TypeScript excitement 😉

TS 6.0 will enable "noUncheckedSideEffectImports" by default 🎉

This increases type safety by erroring if you try to import a non-existent file.

Thanks for @arnaud-barre.bsky.social for pitching & @searyanc.dev for manually coding the PR 👍

github.com/microsoft/Ty...

ECMAScript excitement 😉

Next week's TC39 meeting has a packed agenda:

🔼 Amount
🔼 Array.prototype.pushAll
🔶 AsyncContext
🔶 Await Dictionary
🔼 Import Bytes
🔶 Intl Era Month Code
🔼 Iterator Chunking
🔶 new Global()
🔼 Non-extensible applies to private
🔼 Promise Adoption
🔼 Promise Predicate
🔶 Temporal

This is incredible! Honestly, sometimes I don’t even point folks to MDN and the like anymore - I just point them to your blog posts 🥇

From the latest articles by @una.im & @ishadeed.com on CSS Anchor Positioning, I realized it’s not just for menu and tooltips.

una.im/follow-the-a...
ishadeed.com/article/anch...

It’s more like position: relative across DOM. Like you can make a floating :focus.

Release v5.0.0 · sindresorhus/type-fest Breaking This package is now pure ESM. Please read this. Require TypeScript 5.9 b5b0214 Require Node.js 20 cc2b0f2 Reminder: type-fest requires strict: true in your tsconfig. StringKeyOf: Rename t...

type-fest 5 is out! 🚀

(essential TS types)

Strictness helpers:
- ExtendsStrict
- ExcludeStrict
- ExtractStrict

Checks:
- IsUnion
- IsOptional
- IsNullable

Key-level checks:
- IsOptionalKeyOf
- IsReadonlyKeyOf
- IsRequiredKeyOf
- IsWritableKeyOf

And lots of bug fixes!

github.com/sindresorhus...

Color Shifting in CSS • Josh W. Comeau A little while ago, I was trying to animate an element’s background color, so that it cycled through the rainbow. Seems easy, but it turns out, browsers have a surprisingly big limitation when it comes to color processing! In this tutorial, we’ll dig into the issue, and I’ll share a couple of strategies you can use to work around this limitation.

A while back, I was building a particle animation, and I ran into some weird issues. The particles were turning grey, mid-animation. And sometimes, they wouldn’t change color at all!

Turns out, there’s a pretty big limitation with color transitions. I share some solutions in my brand-new post!

Rolldown drops CJS support!

From the latest version of @rolldown.rs (1.0.0-beta.36) on, Rolldown will only be released in the ESM format.

The required Node version has also been bumped to align with @vite.dev (20.19+ and 22.12+). Node 18 has been dropped due to being EOL since April.

Looks like CesiumJS just released a new Martian data set on Cesium Ion! Controls and rendering work out-of-the-box with 3d-tiles-renderer, as well. Mars rover integration coming... someday? 🤖

Demo link below 👇

#threejs #webgl #gis #nasajpl #3dtiles

Composition with the Shadow DOM is more powerful than you think. You can do a lot with the default named slot assignment, but manual slot assignment is a pathway to many abilities some consider to be… unnatural.</emperor-palpatine>

About 10 months ago I benchmarked the most popular bundlers to compare build speed and bundle size (tree-shaking + minification).

I just re-ran the tests with the latest versions to see what’s changed 👇

Misconceptions about CSS Specificity To remove some of the confusion, here’s a list of misconceptions about Specificity in CSS …

From the archives: “Misconceptions about CSS Specificity”

- Misconception 1: Specificity is a decimal score
- Misconception 2: Using the style attribute (“inline styles”) adds Specificity
- Misconception 3: Using !important adds Specificity

bram.us/2024/05/05/m...

Announcing Rspack 1.5 - Rspack Fast Rust-based web bundler

Rspack v1.5.0 is out! 🎉

⚡️ Barrel file optimization
⚡️ Faster file system watcher
⚡️ Smaller installation size
💪 Extending Rspack with Rust
💪 Type re-export analysis

And many exciting new features...

Read more in our blog:
rspack.rs/blog/announc...

Just filed an issue to turn `--strict` on by default in TypeScript.

Maybe it's a little bit ambitious, but I'm excited for us to try this one. 😄

github.com/microsoft/Ty...

🎉 Preact 11 beta is here! After years of thoughtful development, we're delivering major improvements with minimal breaking changes. Better hydration, forward refs by default, and performance upgrades - all while maintaining the stability you love about Preact X.

View Transitions are enabled by default in Firefox Nightly, so they're on their way to stable. Give it a test with your current transitions, and give me a shout if anything doesn't look right.

The JavaScript Oxidation Compiler A collection of high-performance JavaScript tools written in Rust

Announcing Oxlint Type-Aware Preview

oxc.rs/blog/2025-08...

Why is no one talking about this PR that brings multi-threaded linting to eslint itself 🤯

Tried it out on the @sentry.io codebase and it yields an instant 35% time reduction with `--concurrency=2` in CI 🔥

This is fantastic 🚀