Most accessibility failures come from a short list of causes, and most are cheap to fix. This is what to do first, why it matters, and how to check your work in ten minutes.
JavaScript runs your code on a single thread yet handles thousands of concurrent operations. Understanding the event loop turns async from something you cargo-cult into something you can reason about.
TypeScript is JavaScript with a type checker attached, and every type disappears before your code runs. Here is what that buys you, what it does not, and how to adopt it without rewriting everything.
Most React performance advice is applied to problems that do not exist. Here is what actually triggers a re-render, when it matters, and how to fix the cases that genuinely hurt.
Static, server-rendered, client-rendered or streamed — Next.js gives you all four, per route. Here is what each one costs, what it buys, and how to choose without guessing.
LCP, INP and CLS measure loading, responsiveness and visual stability from the user's point of view. Here is what each one really measures and the fixes that reliably move them.
Flexbox and Grid solved layout properly, and container queries finished the job. Here is when to use each, plus the modern CSS that quietly removed the need for most utilities.
