🎆 I Brought the Cosden Code Bundle Back
Due to a lot of requests, I’ve re-added the Cosden Code bundle for anyone on an annual plan. That means you now get Project React and Advanced React Patterns included, on top of everything already on the platform. It is a huge amount of value if those courses were on your radar, plus all 12+ upcoming courses are still included. And some surprises in the new year 👀. If you are ready to take your React skills seriously in 2026, this is a good time to jump in.

👀 Common useEffect anti-patterns I see in code reviews (and how to fix them)
This thread is a clear, practical breakdown of why useEffect still causes bugs, even in otherwise solid React codebases. What I found useful is how it reframes useEffect as a synchronization tool, not a lifecycle replacement, which immediately clarifies when you should not be using it. The examples around derived state and fetch race conditions are simple but painfully common in real code. If you write or review React regularly, this is a great mental model reset that will save you performance issues and subtle bugs down the line.

😅 React Server Components: Another Urgent Security Update
After I published last week’s newsletter, even more serious issues were uncovered in React Server Components, and this follow up post from the React team explains exactly what changed. It details new high-severity Denial of Service vulnerabilities and a source code exposure issue, including which versions are still unsafe even after last week’s patch. The key takeaway is simple but urgent: some “patched” versions were incomplete and you need to upgrade again to the newly backported releases.
If you run React on the server or rely on frameworks like Next.js or React Router, this is essential reading to avoid outages or accidental source leaks.

📖 A comprehensive guide for building a TanStack Start application with Better Auth
This is a hands-on, opinionated walkthrough of building a real TanStack Start app with authentication, a proper database, and a clean routing model. What I like is that it goes beyond hello world and shows how the pieces actually fit together using Better Auth, Drizzle, and Postgres. It is especially useful if you want less vendor lock-in, lower costs, and more control while still keeping a great developer experience. If you are curious about TanStack Start as a serious alternative to Next or Remix, this is a practical blueprint worth studying.

📺 The Better Way to Build Next.js APIs
This video walks through a better way to build APIs in Next.js 16 using Elysia on Bun, with a focus on speed and full type safety. It shows how Elysia can run inside Next.js while keeping API code clean, fast, and strongly typed. If you want simpler, faster Next.js APIs, check out Josh’s video.

Quick Links

🗣 AWS CEO Explains 3 Reasons AI Can’t Replace Junior Devs
This article pushes back on the lazy narrative that AI will simply replace junior developers, using clear arguments from the AWS CEO himself. What stood out to me is the point that junior devs are often the best at using AI tools, not the worst, and cutting them actually weakens teams. It also explains why removing juniors breaks the talent pipeline and leads to worse long-term outcomes for companies. If you are early in your career or mentoring others, this is a grounded, reassuring take worth reading and sharing.

🤔 Most used programming languages in 2025
This is one of the most trustworthy “state of” reports each year, and the 2025 edition is especially insightful coming from JetBrains. It combines large-scale survey data from over 24,000 developers with thoughtful analysis on tools, AI, productivity, and real work life. What I find most useful is how it surfaces what developers actually want versus what companies measure, especially around productivity and AI adoption. If you want a grounded pulse on the developer ecosystem, not vendor hype, this report is well worth reading.

🧠 The State of AI Coding
This is one of the clearest data driven snapshots of how AI is actually changing software development right now, not just the hype around it. What makes it valuable is the real metrics on PR size, team velocity, and tool adoption, grounded in production usage rather than opinions. The model comparisons are especially useful if you care about latency, throughput, and cost tradeoffs when building coding agents or internal tools. If you want to understand what is really scaling, what is fragmenting, and where teams are gaining leverage with AI, this report is worth your time.

📸 Google Releases Gemini 3 Flash, Its Fastest Frontier Model Yet
Google has released Gemini 3 Flash, a new model focused on high-end reasoning with much lower latency and cost than their larger frontier models. It combines Gemini 3 level intelligence with Flash-class speed, which makes it practical for agentic coding, interactive apps, and multimodal workflows. What I keep hearing is that the time to first token and responsiveness are where it really stands out in real usage. If fast feedback loops matter to your product or workflow, this is a release worth testing.

In this React tutorial, we're going to explore the essential steps for structuring your React application like a senior React developer, ensuring long-term success. Starting with a solid foundation is crucial in web development, preventing collapse as you add new features.

Understanding how to structure your components, your files and folders, where and how to fetch your data, how to handle your utilities and hooks are all very important things to get right at the start so that you can build a scalable application.

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