Flow for TypeScript Users in 2026 — Flow is Meta's mature typed dialect of JavaScript, and over the years its syntax has converged closely with TypeScript's. This post walks through where the two now differ: Flow's stricter defaults reject several crash-prone patterns TypeScript's strict mode accepts, and it adds features of its own, like exhaustive match expressions.

George Zahariev (Meta)

Free Claude Code Course from Anthropic + Master.Dev — Coding is changing fast, and the engineers who thrive will be the ones who direct AI instead of guessing at it. Lydia Hallie from Anthropic teaches exactly that in our Claude Code course, now free for everyone.

Master.dev sponsor

npm v12 to Stop Running Install Scripts by Default — The forthcoming npm v12 will no longer execute preinstall/install/postinstall scripts, unless you explicitly allow them. You can get ready now by using npm 11.16.0 which prints warnings about anything v12 would block.

GitHub

🤖 Code is Cheap(er) — The creator of htmx says that while code is increasingly easy to produce, understanding is still expensive, and “complexity remains our apex predator.”

Carson Gross

How TanStack Cut TypeScript Type-Checking Work by Up to 86% — TanStack Table v9 (now in beta) made its features modular, but the generic types behind that flexibility introduced noticeable editor lag in alpha. This deep-dive shows how the team used tsc diagnostics to cut type-checking work by 62–86%, with lessons for anyone authoring type-heavy libraries.

Kevin Van Cott (TanStack)

🛠️ React Libraries and Tools for 2026 — Every year, Robin updates this post covering his opinionated list of essential React ecosystem libraries.

Robin Wieruch

Your AI Writes Tests That Pass but Prove Nothing. Fix It — Wallaby CLI makes test generation 10x smarter with live coverage and runtime data, using 3x fewer tokens. One skill to install.

Wallaby Team sponsor

Changing the Kindle's Homepage by Editing Hermes Bytecode — The Kindle’s UI now runs on a Hermes-powered JavaScript stack. Here’s how you can edit the bytecode Hermes produces to change the Kindle UI’s behavior.

Nicholas Tarta

📈 Making numpy-ts as Fast as Native — How a TypeScript NumPy port went from 15x slower to matching native, by changing not whether to use WASM, but who owns the bytes.

Nico Dupont

eslint-plugin-unicorn 67.0: More Than 200 Powerful ESLint Rules — Sindre’s set of curated rules has grown a lot, with almost 100 added or updated in the past few weeks alone. Like enforcing better comments, limiting the depth of nested calls, preferring Temporal over Date, and preferring HTTPS over HTTP in URLs. These rules will seriously challenge (and improve!) your code.

Sindre Sorhus et al.

zod-compiler: Compile Zod Schemas into Zero-Overhead Validators — A build-time compiler that plugs into Vite, webpack, et al. and rewrites existing schemas into optimized, tree-shakeable validators. Claims 2–75x faster validation with no source changes and the full Zod API preserved.

Gajus Kuizinas

That Slow Analytics Endpoint? It's a Database Problem — Pipelines, sync lag, stale data. That's the cost of a split stack. TimescaleDB extends Postgres so your app stays fast.

Tiger Data (creators of TimescaleDB) sponsor

📊 billboard.js 4.0: A JavaScript Chart Library Based on D3 — At almost nine years old, billboard.js now has a new, opt-in canvas-based rendering mode (SVG remains the default), smaller bundles, and better performance on large datasets. There are hundreds of demos ranging from donut charts and funnel charts to overlapping bar charts and radar charts.

Jae Sung Park (NAVER)

PolyCSS: CSS 3D Engine for the DOM — Renders textured 3D polygon meshes entirely in the DOM using CSS matrix3d() transforms — no WebGL or <canvas> required. Works with vanilla JS, React, and Vue. There’s a gallery to explore and a live builder if you want to play around.

LayoutitStudio