🗓️ As it's the last issue of 2025, a reminder that JavaScript Weekly moves to Tuesdays in January. See you again on January 6, 2026! __ Your editor, Peter Cooper
JavaScript Weekly
It's the final issue of the year, so we're going to cover a few new items, then look back at the top links of 2025 (based on reader engagement) and recap what happened in the ecosystem month-by-month this year.
The JavaScript Bundler Grand Prix — Bundlers now sit at the heart of many JavaScript workflows and are sometimes even integrated into runtimes (e.g. Bun’s). This piece surveys the landscape and argues the speed wars are mostly over, with the real battle shifting to artifact size and the code that actually ships to users.
1.A Perplexing JavaScript Parsing Puzzle — Hillel's deceptively simple puzzle – just 14 bytes of code – attracted by far the most attention this year. Despite working with JavaScript for most of its lifespan, I got it wrong!
4.How the Web is Using JavaScript — The JavaScript section of this year's HTTP Archive Web Almanac report went into depth on how much JS we’re using (and failing to use), the popularity of TypeScript, Web Worker usage, and.. yes, jQuery still dominates!
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Trigger.dev handles queues, retries, and long-running tasks so you can build production-ready agents and TypeScript workflows reliably at scale.
🎄 This is the final issue of JavaScript Weekly for 2025 – thanks for reading, submitting links, and supporting us! We're going to return on Tuesday, January 6, 2026. See you then! And, if we're really lucky, we might catch up on our inbox packed with submissions by then too... ;-)
Useful Patterns for Building HTML Tools — In many situations, you don’t need a full-on framework to build useful tools; just HTML, JavaScript and CSS in a single file will do the job fine. Simon’s become a bit of an expert by rolling out many such tools using LLMs, and shares his process and practices here. More please!
Simon Willison
Why Are the Top AI Companies Choosing SpreadJS? — Because SpreadJS brings a familiar Excel-like UI to JavaScript web apps. Trusted by leading AI innovators and organizations, it empowers devs to build finance, analytics, and more apps with Excel I/O, 500+ calc functions, charts, & more. View demos!
SpreadJS From MESCIUS sponsor
Deno 2.6 Released — The popular alternative runtime introduces a new npx-like tool called dx to run binaries from npm and JSR packages, adds a deno audit tool for identifying vulnerabilities in dependencies, adds more granular control over runtime permissions, implements source phase imports, and more.
🔒 GitHub shares an update on its npm token policies. All npm classic tokens have been revoked this week, and there's now a new process for getting a two hour session token or a granular access token instead.
A Proposal for Making Complex Web Apps Faster — From Microsoft comes an early-stage look at a proposal for a new Delayed Message Timing API to help deal with the slowdowns that multiple parallel contexts (iframes, threads, multiple windows, etc) can introduce. Feedback is being sought.
Building a Tiny 2D Physics Engine in JavaScript — A lovely, and rather old-school style post about building a simple physics engine from scratch in JavaScript then golfing it down to just 2KB of source as seen on its homepage (where there's a demo too).
💡 You don't need to be a Remix user to benefit from this code, either. For example, here's the code to the store's neat 'glitchy' 404 page which you could adapt to use elsewhere.
Toastflow: A Toast Notifications Library for Vue 3 — A really nifty web-based playground for playing around with toast notifications. I wish more projects had things like this. Toastflow is technically framework agnostic, but the only renderer so far is for Vue 3. GitHub repo.
Inertia 2.3 – Build single-page React, Vue and Svelte apps using classic server-side routing and controllers (ideally for integrating with server-side frameworks like Django, Rails, Laravel, etc.)
Some other interesting tidbits in the broader landscape:
📺 Earlier this year, Dimitri Mitropoulos wowed us by running Doom inside TypeScript's type system – now he's back ▶️ showing off TypeSlayer, a tool for diagnosing and fixing TypeScript performance problems with some fantastic 3D visualizations. It looks great, but isn't public yet.
Get up to speed with the latest developments in the world of CSS this year with the Chrome team's CSS Wrapped 2025.
🗳️ Rick Viscomi of the Google Chrome team has put out a call for you to vote for the web features you want to see in the future. This is a separate effort from the recent Interop 2025 voting process and votes will accumulate over the long term.
Over thirty years, JavaScript has cemented its place at the heart of the Web platform, and more broadly in desktop apps, operating systems (e.g. Windows' use of React Native), mobile apps, and even on microcontrollers.
P.S. Enjoy finding the 1995 references in our special birthday montage above.
How to Ship Enterprise Auth, Identity, and Security Features — Enterprise customers demand SSO, SCIM, RBAC, and audit logs that meet strict compliance standards. WorkOS offers developers a platform for shipping these features fast with a suite of easy-to-integrate APIs and a portal for streamlined customer onboarding.
WorkOS sponsor
Progress on TypeScript 7 — It’s been a quiet few months for the TypeScript project publicly, but behind the scenes they’ve been working hard on both TypeScript 6.0 and 7.0. v6.0 is going to be the final JavaScript-based release and act as a stepping stone to the native Go port (v7.0) which is already shaping up to be some 10x faster.
Daniel Rosenwasser (Microsoft)
Anthropic Acquires the Bun JavaScript Runtime — It’s been an intense few years for Bun, the JavaScriptCore-powered JS/TS runtime. Anthropic, best known for its Claude LLMs, is betting on Bun for powering its Claude Code agentic development tool and more. Jarred tells the full Bun story here and reassures us Bun will remain open and become better than ever as a result.
The Nuances of JavaScript Typing using JSDoc — If you prefer JavaScript over TypeScript (and I know there are plenty of you!) but still want some of the benefit of types, JSDoc provides an interesting alternative.
🤖TanStack AI: A Unified Interface for LLM/AI Providers — The latest member of the rapidly growing TanStack family of libraries offers a unified, framework agnostic interface to multiple AI APIs, complete with streaming, and Zod schema inference. Currently in alpha.GitHub repo.
TanStack
💡 Another newcomer is TanStack Pacer which offers framework-agnostic debouncing, throttling, rate limiting, queuing, and batching utilities.
Remend: Automatic Recovery of Broken Streaming Markdown — Bring intelligent incomplete Markdown handling to your app, particularly useful if working with LLMs, say. It’s extracted from Vercel’s Streamdown library, a drop-in replacement for react-markdown, designed for AI-powered streaming.
Hayden Bleasel (Vercel)
Tinybench 6.0: A Tiny, Simple Benchmarking Library — Uses whatever precise timing capabilities are available (e.g. process.hrtime or performance.now). You can then benchmark whatever functions you want, specify how long or how many times to benchmark for, and get a variety of stats in return – it runs across multiple runtimes. GitHub repo.
Tinylibs
Ruby2JS: A Ruby to JavaScript Transpiler — A transpiler aimed at keeping the resulting code looking ‘hand crafted’ rather than merely transpiled. Play with the live demo on the home page to get a feel for it.
Sam Ruby and Jared White
Chokidar 5.0 – Efficient cross-platform file watching library for Node.js.
Prisma 7.1 – Popular ORM for Node.js and TypeScript.
Some other interesting tidbits in the broader landscape:
🤖 Colin Eberhardt looks into using GitHub's Spec Kit for building a modern Svelte app using Spec-Driven Development (SDD) where the human and AI agents work in tandem.
DepX's badge generator gives you a graphical badge you can include in your README or on your project site to show how many (or how few!) dependencies your npm package has.