React in its sigma era

React 19.2: React in its sigma era
5 minutes by Anju Karanji

React 19.2 introduces a compiler that automatically handles optimization, removing the need for manual memoization. The Activity component keeps components in the background instead of fully unmounting them, preserving state. New debugging tools in Chrome DevTools show detailed performance breakdowns of renders and components. The framework also improves server-side rendering by batching loading states together for smoother user experiences.

MCP Authorization in 5 Easy OAuth Specs
sponsored by WorkOS

Securely authorizing access to an MCP server used to be an open question. Now there's a clear answer: OAuth. This guide breaks down the five specs that make it work in practice, covering delegation, token exchange, and scoped access. WorkOS packages everything into one API so you can skip building your own OAuth stack.

Synchronizing timers in React
3 minutes by Karol Działowski

Karol introduces a React hook that synchronizes timers across multiple components. The problem occurs when different components use separate intervals with the same delay, causing them to run out of sync. The solution creates shared "buckets" that group callbacks by their delay time. All callbacks in the same bucket execute simultaneously when the interval fires. This keeps components independent while ensuring their timers stay synchronized.

React 19 error boundary behaves differently
2 minutes by Andrei Calazans

React 19 changed how error boundaries handle multiple errors within the same boundary. Previously, React would attempt to render each failing component twice and log duplicate errors. Now it stops after the first error occurs and skips rendering sibling components that share the same error boundary. This reduces unnecessary resource usage and eliminates duplicate error logs, allowing developers to simplify their error handling code.

Everything you need to know about act() in tests
11 minutes by How to test frontend

React’s act() function ensures state updates and side effects are fully processed before assertions run, preventing tests from reading stale UI. The article explains what act() does, when it’s required, and how React Testing Library often handles it automatically. It also covers common warnings, debugging steps, and best practices to avoid unnecessary act() usage while keeping tests accurate and reliable.

Don't blindly use useTransition everywhere
6 minutes by Nicolas Charpentier

React's useTransition hook is often recommended for improving user experience, but it can create poor UX when misused. The basic documentation example shows a tabbed interface where clicking a slow tab shows a "pending" state while displaying old content, which feels confusing. Nicolas suggests better approaches like using a Delay component to yield control back to React, or combining it with useTransition for more control.

Feature complete ≠ spec complete. Bring Figma, Jira, and Linear context into your pull requests.
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React in its sigma era

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