Hey everyone,

I've been preparing for frontend interviews and couldn't find a quiz tool I liked, so I built one: devsets.com

What's inside:

• 2,700+ questions across 12 topics (JavaScript, TypeScript, React, Next.js, Angular, Vue, Svelte, HTML & CSS, state management, testing, patterns, system design)
• Junior / Middle / Senior levels, and every answer comes with an explanation and links to the docs
• Interview mode with a timer per question
• Stack quizzes (e.g. "React Developer") that mix several topics like a real interview
• Spaced repetition: questions you got wrong come back after 1, 3 and 7 days
• 18 JavaScript coding tasks (debounce, deepClone, Promise.all...) with tests that run in the browser

It's free, ad-free and works without an account (sign in only if you want to sync progress). Available in English, Ukrainian and Polish.

I'd really appreciate feedback: wrong answers, confusing questions, missing topics, anything. Every question has a "report a problem" button too.

A few months ago I wrote about the React Compiler, and my advice for existing code was to leave useMemo and useCallback alone at first, then clean them up slowly, with tests, once the compiler has been running for a while.

I'm curious how that went for people who actually did it.

The public numbers I found are from InfoQ's write-up: Sanity saw 20-30% less render time and latency on their Studio packages (1,231 of 1,411 components compiled on the first pass), and Wakelet's INP went from 275ms to 240ms.

If you're running it in production, did you rip out the manual memoization? Did anything break?

My article, if you want the details on the compiled output: https://neciudan.dev/react-compiler-explained