Mathias Bynens

At #io19, @_gsathya and I gave a talk on cutting-edge JavaScript features: youtube.com/watch?v=c0oy0v… ➡️ WeakRef ➡️ Intl.* ➡️ Promise.{allSettled,any} ➡️ numeric separators ➡️ Array#{flat,flatMap} ➡️ Object.fromEntries ➡️ String#matchAll ➡️ …and more!

@addyosmani @markgoho Closing the loop: we shipped this last week!

@markgoho github.com/ChromeDevTools… for discussion :) (shape of proposal is not 100% "there", but right direction) cc @mathias

Chrome just became massively more agent-friendly 🔥 Your real, signed-in browser can now be natively accessible to any coding agent. No extensions. No headless browser. No screenshots. No separate logins. Just one toggle to enable it. Check this out: developer.chrome.com/blog/chrome-de…

@addyosmani @alperortac Currently chrome-devtools-mcp supports global network throttling, but not on a per-request basis (yet). To help us prioritize per-request throttling support in chrome-devtools-mcp, please file a feature request with a motivating use case here: github.com/ChromeDevTools…

@alperortac Paging @mathias as he may be able to confirm

Chrome DevTools now supports *individual* network request throttling! Folks have been asking for this for years! DevTools now allows developers to simulate slow network conditions for specific requests rather than the entire page. This helps in testing how a web application performs and handles issues when specific resources (like images, scripts, or API calls) are slow to load.

@elsigh @addyosmani @ChromeDevTools It's part of the config. The readme has an example: #configuration" target="_blank" rel="nofollow noopener">github.com/ChromeDevTools…

@addyosmani @ChromeDevTools rn I see "Error: The browser is already running for /Users/elsigh/.cache/chrome-devtools-mcp/chrome-profile. Use --isolated to run multiple browser instances." (not sure how to pass a flag to chrome-devtools-mcp)

Announcing @ChromeDevTools MCP! 🚀 Connect your AI coding agent to Chrome's powerful automation & debugging capabilities with ease. Key features: ✅ Reliable automation: It can programmatically handle clicks, form fills, dialogs, and page navigation with ease. ✅ Performance insights: Go beyond simple audits. Instruct your agent to record a performance trace and extract actionable insights to optimize your web apps. ✅ Advanced debugging: Empower your AI to analyze network requests, list console messages, take screenshots, and even evaluate scripts in the browser context. ✅ Browser emulation: Easily test different conditions by emulating CPU slowdowns, network throttling, or various screen sizes. Works well with modern web apps and believe this will unlock new workflows for automated testing, AI-driven debugging, and interactive web development. And there's much more to come!

@domenic Congratulations Domenic!

I'm retired! domenic.me/retirement/

@guntrambechtold My favorite use case so far! 🏆

Wow! Thats how you can use Chrome DevTools MCP to glow-up Hacker News's minimalist aesthetic. And I'm not sorry. Its pure CSS chaos: rainbow gradients, spinning rank numbers, Comic Sans headers (48px!), bouncing links, glowing neon text effects. Even added floating emojis across the entire page. The fact that I can inject code and manipulate any webpage programmatically through this MCP integration is mind-blowing. This is the browser automation I've been waiting for. Seriously impressive work on this tool. Game changer. Love it. Thank you @mathias and team!

Unicode 17 is released. The process for upgrading in js tooling is: 1. wait for @mathias to land unicode 17 in test262, e.g. github.com/tc39/test262/p… 2. in js, upgrade to `@unicode/unicode-17.0.0`, e.g. github.com/babel/babel/pu… 3. in Rust, upgrade github.com/oxc-project/un…, which I maintain. blog.unicode.org/2025/09/unicod… jenniferdaniel.substack.com/p/tomorrows-em…

The src attribute on <img> is no longer required. github.com/whatwg/html/is…

@deeheber @brianleroux @begin @sanity_io Congrats!!!

Ever spent ages trying to figure out which element is actually scrolling on a page? #ChromeDevTools added a new scroll badge to help you spot them easier! Ionut & @jecfish will walk us through the technical implementation behind the scenes. Read: developer.chrome.com/blog/swe-devto…

✈️💺 Fasten your seatbelts! DevTools got a turbocharged upgrade with the new AI assistance panel. Debug styling issues, understand layouts, and fix airplanes. Ready for take-off? ➡️ developer.chrome.com/blog/5-cool-th…

Introducing AI Assistance in @ChromeDevTools! 🤯🚀 Ever wish you could have a coding buddy to help you with CSS and layout? Well, your wish is granted! The new AI Assistance in Chrome DevTools is here to make your life as a developer easier, powered by Gemini. The new panel aims to help you find and fix issues. Just ask it questions about your code, and it provides tailored explanations and even suggests solutions. This is our first exploration into agentic AI in DevTools and we're excited to hear what you think of it. Some key features: 1. Conversational prompts: Get tailored suggestions and code snippets. 2. Contextual understanding: AI understands the code you're working on. 3. Step-by-step guidance: Get help with everything from styling to debugging. Want to see it in action? Check out my screencast below to see how I used it to add a dark mode.

✨ More Gemini is coming to DevTools! ✨ Try the new experimental AI assistance panel in Chrome Canary 131 and later to get help understanding layouts and debugging your CSS. Learn more at goo.gle/devtools-ai-as…

@philhawksworth Congrats Phil!

📢 New post: The State of ES5 on the Web. For years, we defaulted to transpiling to ES5 in order to support IE. But is that still necessary? I took a look at the data to find out, and I'll just say that the results were *actually* quite surprising! 🙀 philipwalton.com/articles/the-s…

@argyleink I’m intuitively assuming any browser code that parses HTML is more highly optimized than any browser code that parses these elaborate OpenType contextual alternates — but I haven’t actually measured this so I don’t know! cc @abrax5

@argyleink Loving this! I wonder how this impacts rendering performance. One of the main reasons folks use build-time syntax highlighting with simple HTML + CSS is to minimize the runtime performance cost. This OTOH seems to put at least some of that cost (“parsing”) back on the user.

no pain syntax highlighting‽ - no JS - no markup transformation or tokenization how? via Colr Fonts 💪 try it! codepen.io/argyleink/pen/…

Ahead of Defcon, the always-brilliant @SamyKamkar gave me a preview of his infrared laser spy tool: He can point a laser through a window at a laptop to detect its vibrations and derive the words typed on it from the acoustics of different keystrokes. wired.com/story/infrared…

We’re pleased to announce that, as of version 23, the Puppeteer browser automation library now has first-class support for @Firefox! This means simplifying browser automation and testing across both @googlechrome and Firefox. 💻 hacks.mozilla.org/2024/08/puppet…