Show HN: Get your coding agent off ~2019 JavaScript, onto modern web primitives
Browsers natively handle a lot of what used to take 50 lines of JS (or a dependency): `CSS.highlights` for text range highlighting without <span>s everywhere, `<dialog>` and showModal() give you backdrops and ideal focus management, `field-sizing` to auto-grow textareas as the user types.. (Something yesterday's ftrain post touched on [0]) Models know about some of these by name, but consistently won't default to using the platform-native solution and instead prefer the incumbent <div>+JS based pattern. We started an effort in Chrome to supplement coding agents with this key domain knowledge and we're shipping our 1.0 today, in collaboration with Firefox, MDN, and Edge. 200+ guides (~1.7MB) of curated, hand-crafted implementation best-practices from web experts, updated as the web evolves. (Open source, obv, so.. we'll welcome your bikeshedding ;) Readable versions here: [1] I've spent the last 9 months obsessing over how to ship this as an agent skill + (Agentic RAG) CLI without blowing up your context window. (Or cedeing activation mechanics to MCP dynamic tool search). The skill description is minmaxed for activating on relevant frontend tasks. The RAG work I'm pretty proud of… originally a 500mb native stack down to a ~7MB pure-JS package, ~10ms search on your CPU. We just introduced a deterministic 'legacy-scan' (trained on 30k github repos) to identify old 'n dusted patterns that your agent can modernize. (92% avg precision on held-out repos.) People make a lot of claims about what coding agents are good/bad at. We wanted receipts, so we invested heavily in eval infra [2] to help us hill-climb, but also to identify when knowledge is common enough we can prune our guides. (Ofc, some of the things we thought AI didn't know turned out to be wrong :) We run codex/claude/agy against 200 tasks without the skill and then with.. In total ~1,700 playwright/AST-based assertions. Agents go from 55% pass unguided to 92% guided. Try it out: DISABLE_TELEMETRY=1 npx modern-web-guidance@latest install DISABLE_TELEMETRY=1 npx modern-web-guidance@latest search "animate dialog modal" DISABLE_TELEMETRY=1 npx modern-web-guidance@latest legacy-scan ./src If you spot something wrong or weird, give us a holler! Longer write-up on the 1.0: https://developer.chrome.com/blog/modern-web-guidance-v1 --- 0: https://news.ycombinator.com/item?id=50416456 1: https://developer.chrome.com/docs/modern-web-guidance/guides 2: https://googlechrome.github.io/modern-web-guidance-src/
Discussion Highlights (20 comments)
phyzix5761
"Best Practices" are pretty much dead in the AI era. Pretty soon no one is going to read any of the code AI produces and that's a scary thought.
halflife
Finally. This is exactly what I need when I need it. The amount of pull requests I reviewed with a mess of codes that can be switched to 2 lines of modern features made me write such tools myself, only half assed since I have other things to do.
cyanydeez
I treat all my code as some kind of stochastic machinery. So atleast one stage, I'd just tell an agent to go through and follow the guide. But I'd not inject all this fluff into the wheels of the machine because it'd just take the "average" of these practices which would be just as useless.
simonw
Distribution suggestion: in addition to the npm packages you have right now, set up GitHub Pages to publish a markdown index document of the skills at https://googlechrome.github.io/modern-web-guidance-src/skill... (currently a 404) That index page should link to plain markdown versions of all of the documents, and should be designed for search with grep to find the right answers. That way I don't have to install anything at all - provided my agent has the ability to make HTTP requests I can tell it "Look for tips on https://googlechrome.github.io/modern-web-guidance-src/skill... " and it will fetch the index, then navigate to the most relevant documents - no MCP or npm or installation required at all.
advisedwang
Chrome already has too much power in the browser standards world. The last thing we need is everyone's LLMs to follow Chrome team's guidance on how to do web development. This road leads back to "To view this site, please view in [DOMINANT BROWSER]"
zeroq
What's the best way to introduce this to a Gemini chat?
fumar
I added this a few months ago and Claude Doctor has not removed it. It must be working and getting use.
reedlaw
These skills look better than most, but running my code through the legacy scan only found two issues. So while I still think training beats skills, I'm sure this has its place, especially with weaker models.
j45
This is a great idea. I think while so much was being built out in the JavaScript ecosystem, awareness about the equivalent feature releases that were done to HTML, CSS, web components, and other technologies didn't keep pace. Of course, it's not perfectly implemented the same in every browser, but that's nothing new.
cadamsdotcom
Planning to give this one a wide berth. The more "legacy code" is getting written everyday the more the web will be forced to remain backwards compatible...
PenguinRevolver
I use Firefox after Chrome decided to become a bit of a pain to use on my powerful computers. I was unsure how bias the skills were for Chrome exclusive features, so I decided to ask ChatGPT to analyse the repo. I liked the answer it gave, so here it is: https://chatgpt.com/share/6af3712a-03cc-83eb-ad1f-66dd11c886...
gabrieledarrigo
That's pretty cool! On the other hand, a bit sad: programming nowadays is just arranging a bunch of Markdown files, possibly generated by another bunch of models. Not so exciting, in the end.
chalmovsky
Amazing! I'm just writing an article about how Alex Russell's quote about 'React being a legacy technology' got, unfortunately, totally ignored. And now this just fell in my lap! Some of the arguments I wanted to make seem to be provide here. Didn't have a chance to take a proper look at it, but it looks very promising and nice! Thank you!
surround
Here's a list of browser features the skills will tell your agent to use that are stable in Chrome but not supported by Firefox and Safari: CSS @function CSS calc-size() CSS interpolate-size CSS corner-shape CSS border-shape CSS flex-wrap: balance CSS text-fit CSS text-decoration-skip-spaces CSS scroll-axis-lock CSS scroll-target-group CSS :target-current CSS scroll-initial-target CSS container scroll-state queries scrollsnapchange event scrollsnapchanging event HTML focusgroup Element.startViewTransition() CSS view-transition-scope Interest Invokers (interestfor) LanguageModel (Prompt API) LanguageDetector Translator Summarizer API Window.fetchLater() Speculation Rules API Long Animation Frames API VisibilityStateEntry PerformanceSoftNavigation InteractionContentfulPaint Connection-Allowlist CSS url() integrity() modifier HTML meta name="text-scale" HTML template for HTML processing instructions PasswordCredential Promise-returning scroll methods Web App Origin Migration Local Network Access permissions Request.targetAddressSpace beforeinstallprompt event To be fair, the skills also recommend ~11 features not supported by Chrome itself. And the project does seem concerned with compatibility: "Guiding models to use sensible, lightweight fallbacks."
dallen33
Paul Irish?? There's a name I haven't though about in ages! I remember following you on Twitter and your website was full of amazing information. Hope you're doing well!
internet2000
NO THANK YOU. Do not want my agents to contribute to the Chrome monoculture. Chrome is the new IE6.
adzm
I find this very useful as a human as well
mococa
More Chromish on web? No thanks.
tonymet
I recommend saying "contemporary" or "suggested" for transient proposals like this. Having modern change every few years is ambiguous and cliche . These concepts are new, so no one knows if they are any good. They're not modern -- who knows if they will even be put to use? "contemporary", "proposed", "suggested", "compatible" are better fit. I wouldn't dare use "advanced" because many APIs and proposals actually regress earlier behavior.
pyrolistical
I asked my agent to look at that list and only apply things that work on chrome, Firefox, safari iOS and safari macos Came up with a good list for my project