alt Hacker NewsShow 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
Longer write-up on the 1.0: https://developer.chrome.com/blog/modern-web-guidance-v1
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0: https://news.ycombinator.com/item?id=50416456
1: https://developer.chrome.com/docs/modern-web-guidance/guides
Comments
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]"
"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.
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.
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.
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...
I added this a few months ago and Claude Doctor has not removed it. It must be working and getting use.
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.
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...
What's the best way to introduce this to a Gemini chat?
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.
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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.
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.