Most TypeScript users have heard of template literal types and don't use them. They are the feature that turns "string with a specific shape" into a checked type. Here are the four practical patterns — typed routes, prefixed keys, builder methods, validation — that show up in every real codebase.
Most React apps still spell out `if (loading) … if (error) … if (data)` in every component. Suspense + an error boundary collapses all three into the JSX tree above. Here is the working pattern with React Query / SWR, the streaming SSR story, and the trap that makes Suspense look slow.
Cypress invented the modern E2E testing experience. Playwright surpassed it on capability, speed, and parallelism. Here is the side-by-side that matters: real-world test runtime, which APIs are stable, the cross-browser story, and the migration cost if you're already on Cypress.
Vite's dev experience is dramatically better than Webpack's — sub-second hot reloads versus 30 seconds. The migration is real work though, and not always worth it. Here is the realistic comparison, the migration patterns that succeed, and the cases where Webpack is still the right tool.
React Server Components confuse most developers because the mental model is unfamiliar. The fix is to think of the boundary as “where in the tree does this code need to be reactive?”. With that lens, every component decides itself whether it is a server or client component.
Most “PWA support” is a manifest.json and an install prompt. Real offline-first apps need a service worker that handles caching, navigation fallbacks, and background sync. Here is the 80-line service worker that gets you a working offline experience and the three traps that crash your app the first time the network comes back.
HTTP/3 fixes head-of-line blocking that HTTP/2 introduced, but most apps will never feel the difference. The wins are concentrated in mobile, lossy networks, and CDN-served static assets. Here is the technical difference, the cases where it actually matters, and the cases where it doesn't.
Most websites ship 2 MB hero images for slots that render at 600 px wide. The fix is half configuration and half discipline: a CDN that does on-the-fly format negotiation, srcset that picks the right size, and the four `<img>` attributes that move every PageSpeed metric.