Functional programming jargon, mapped out

#​802 — September 15, 2026

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JavaScript Weekly

Functional Programming Jargon, Mapped and Explained — Currying, purity, functors, monads…? If FP terms ever go over your head, TC39 delegate Hemanth HM's popular jargon reference is now an explorable map of concepts showing how they relate, each with a simple definition and JavaScript example.

Hemanth HM

Stay Sharp in the Age of AI — Master.dev instructors build at Anthropic, OpenAI, Netflix, Google, and Stripe. Learn from them with hundreds of courses, live workshops, and expanded AI learning paths. New members get $100 off a yearly membership.

Master.dev sponsor

Modern Web Types: TypeScript Support for Newer Web APIs — TypeScript's DOM types only include APIs shipped in multiple browser engines, so things like element-scoped startViewTransition and fetchLater throw up errors. modern-web-types is a drop-in lib.dom replacement that adds missing interfaces/members shipped in any single browser engine.

Philip Walton (Google)

React 19.3 Released — A significant minor release making view transitions and Fragment Refs stable, adding Trusted Types support, and more. We covered it in more depth in last week's React Status.

The React Team

IN BRIEF:

• 🔒 Attackers are scanning for exposed Vite dev servers exploiting a server.fs.deny bypass (patched in Vite 7.3.2 and 8.0.5 earlier this year) to grab credentials from .env files. Vite listens on localhost by default, but double check your setup.
• Safari 27 shipped yesterday (alongside macOS/iOS 27), bringing the module loader rewrite we covered last week, so top-level await now works reliably in all major browsers.
• TC39 meets in Tokyo in two weeks. Here's the agenda with three iterator helper follow-ups (join, includes and chunking) all up for Stage 4, plus more.
• 🔒 Starting this Thursday, the OpenJS Foundation's CVE team is taking a break till October 6 due to burnout driven by a surge of AI-generated reports. Actively exploited issues will still get a response.
• 🔒 npm now places a temporary 72-hour 'security hold' on any account after a successful recovery-code sign-in.

RELEASES:

• pnpm 12.4 – The package manager can now manage Rust crates and Python packages alongside npm ones in a single workspace.
• Playwright 1.63 – Tests can now declare a named lock so those sharing a resource never run concurrently.
• Node.js v26.8.2 (Current) and v24.21.0 (LTS) – Both include a security release of Undici to fix numerous vulnerabilities.
• React Router 8.4, Vite 8.3, Moment.js 2.31.0 (security release).

📖 Articles and Videos

A Design Space Exploration of async/await — A simple async/await example produces different results in JavaScript, Rust, Python and Swift. Test your mental model with a quiz, then learn about the design choices behind the differences.

Gavin Gray

Native is Now the Future of Mobile at Shopify — Shopify is rewriting its React Native mobile apps in Swift/Kotlin. The main argument is coding agents have cut the cost of writing everything twice, while the upsides of native remain.

Mustafa Ali (Shopify)

Workshop: From an Error to the Logs That Explain It — Reading logs next to traces and errors, holding context across services, and cutting the noise.

Sentry sponsor

A Deep Dive into StyleX — A hands-on tour of Meta's StyleX, which turns JavaScript style objects into plain atomic CSS at build time, and why it can be a good fit for coding agents in particular.

Flavio Copes

📄 'Nobody Pays for Open Source: We Can Force Them To' – Laurie Voss ran npm for five years and thinks registries are an untapped lever for funding maintainers. Laurie Voss

📄 Anecdotally, Programmers Dislike reduce – map and filter sail through code review, but reduce draws complaints. Evan has a few theories why. Evan Hahn

🛠 Code & Tools

SnapDOM 3.0: Turn DOM Elements Into Images, Canvas and More — Zero-dependency html2canvas alternative with support for pseudo-elements and Shadow DOM. v3.0 adds 'incremental recapture' for faster repeat captures, automatic web font embedding, and fromString() for turning raw HTML markup into images.

Zumerlab

Your App Didn't Get Slower. Your Data Got Bigger — TimescaleDB extends Postgres so queries stay fast at scale, even as your data grows. Get $1000 credit to start.

Tiger Data (creators of TimescaleDB) sponsor

Fallow: Codebase Intelligence for TypeScript and JavaScript — A fast, zero-config Rust binary that finds dead code, duplication, circular dependencies and complexity hotspots in JS/TS projects. It's also pitched as a deterministic check for AI agent coding loops. GitHub repo.

Bart Waardenburg

🎨 category-colors: Generate 'Least Wrong' Color Palettes for Charts — Matt devised this algorithm for picking categorical chart colors in 2022 while design director at Stripe. It's now available as an npm package, and you can try it out on the Web here.

Matt Ström-Awn

• React DevTools 8.0 (Chrome Web Store) – The Suspense tab is now on by default, the Timeline profiler is gone (use your browser's Performance panel instead), and inspecting a DOM node now shows its matching React component.
• Zod 4.6 – Adds .validate(), a boolean check that skips building errors and is up to 35x faster than .safeParse().success on invalid input with compiled schemas.
• Javet 6.0 – Embed Node.js v26's runtime in the JVM for full interop with Java.
• parse-xml 5.0 – The fast, compliant XML parser goes ESM-only.
• 🕹️ n64js 1.0 – A Nintendo 64 emulator in pure JavaScript.

📰 Classifieds

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📢 Elsewhere in the ecosystem

• 🕹️ This year's js13kGames entries are in with a record 317 games squeezed into 13KB each. Frank Force's SP13KTRA racer and the Hornbound roguelike are good places to start, and you can dig around the public repos of every project too.
• Chris Coyier rounds up new and emerging HTML features worth knowing about, like the and elements, as well as HTML-in-Canvas and improvements to customization.
• The first Three.js Conference took place in Paris last week, and Codrops has a live-blog writeup of both days, including Mr.doob's talk. No recordings yet.
• Tailwind Labs, the team behind Tailwind CSS, is joining Shopify. Tailwind CSS is to remain maintained and open source – phew! 😅