Temporal: The 9-year journey to fix time in JavaScript

A better streams API is possible for JavaScript

UEFI Bindings for JavaScript

The JavaScript Oxidation Compiler

Hi HN, we&#x27;re Sam, Shane, and Abhi.Almost a year ago, we first shared Mastra here (<a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=43103073">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=43103073</a>). It’s kind of fun looking back since we were only a few months into building at the time. The HN community gave a lot of enthusiasm and some helpful feedback.Today, we released Mastra 1.0 in stable, so we wanted to come back and talk about what’s changed.If you’re new to Mastra, it&#x27;s an open-source TypeScript agent framework that also lets you create multi-agent workflows, run evals, inspect in a local studio, and emit observability.Since our last post, Mastra has grown to over 300k weekly npm downloads and 19.4k GitHub stars. It’s now Apache 2.0 licensed and runs in prod at companies like Replit, PayPal, and Sanity.Agent development is changing quickly, so we’ve added a lot since February:- Native model routing: You can access 600+ models from 40+ providers by specifying a model string (e.g., `openai&#x2F;gpt-5.2-codex`) with TS autocomplete and fallbacks.- Guardrails: Low-latency input and output processors for prompt injection detection, PII redaction, and content moderation. The tricky thing here was the low-latency part.- Scorers: An async eval primitive for grading agent outputs. Users were asking how they should do evals. We wanted to make it easy to attach to Mastra agents, runnable in Mastra studio, and save results in Mastra storage.- Plus a few other features like AI tracing (per-call costing for Langfuse, Braintrust, etc), memory processors, a `.network()` method that turns any agent into a routing agent, and server adapters to integrate Mastra within an existing Express&#x2F;Hono server.(That last one took a bit of time, we went down the ESM&#x2F;CJS bundling rabbithole, ran into lots of monorepo issues, and ultimately opted for a more explicit approach.)Anyway, we&#x27;d love for you to try Mastra out and let us know what you think. You can get started with `npm create mastra@latest`.We&#x27;ll be around and happy to answer any questions!

Show HN: Mastra 1.0, open-source JavaScript agent framework from the Gatsby devs

JavaScript-heavy approaches are not compatible with long-term performance goals

We needed a JS-first WYSIWYG DOCX editor and couldn&#x27;t find a solid OSS option, most were either commercial or abandoned.As an experiment, we gave Claude Code the OOXML spec, a concrete editor architecture, and a Playwright-based test suite. The agent iterated in a (Ralph) loop over a few nights and produced a working editor from scratch.Core text editing works today. Tables and images are functional but still incomplete. MIT licensed.

Show HN: JavaScript-first, open-source WYSIWYG DOCX editor

Hi HN,
I’m a chemical engineer and I manage logistics at a refinery down in Texas. Whenever I try to explain downstream operations to people outside the industry (including my kids), I usually get blank stares. I wanted to build something that visualizes the concepts and chemistry of a plant without completely dumbing down the science, so I put together this 5-minute browser game.Here&#x27;s a simple runthrough: <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=is-moBz6upU" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=is-moBz6upU</a>. I pushed to get through a full product pathway to show the V-804 replay.I am not a software developer by trade, so I relied heavily on LLMs (Claude, Copilot, Gemini) to help write the code. What started as a simple concept turned into a 9,000-line single-page app built with vanilla HTML, CSS, and JavaScript. I used Matter.js for the 2D physics minigames.A few technical takeaways from building this as a non-dev:
 * Managing the LLM workflow: Once the script.js file got large, letting the models output full file rewrites was a disaster (truncations, hallucinations, invisible curly-quote replacements that broke the JS). I started forcing them to act like patch files, strictly outputting &quot;Find this exact block&quot; and &quot;Replace with this exact block.&quot; This was the only way to maintain improvements without breaking existing logic.* Mapping physics to CSS: I wanted the minigames to visually sit inside circular CSS containers (border-radius: 50%). Matter.js doesn&#x27;t natively care about your CSS. Getting the rigid body physics to respect a dynamic, responsive DOM boundary across different screen sizes required running an elliptical boundary equation (dx * dx) &#x2F; (rx * rx) + (dy * dy) &#x2F; (ry * ry) &gt; 1 on every single frame. Maybe this was overkill to try to handle the resizing between phones and PCs.* Mobile browser events: Forcing iOS Safari to ignore its default behaviors (double-tap zoom, swipe-to-scroll) while still allowing the user to tap and drag Matter.js objects required a ridiculous amount of custom event listener management and CSS (touch-action: manipulation; user-select: none;). I also learned that these actions very easily kill the mouse scroll making it very frustrating for PC users. I am hoping I hit a good middle ground.* State management: Since I didn&#x27;t use React or any frameworks, I had to rely on a global state object. Because the game jumps between different phases&#x2F;minigames, I ran into massive memory leaks from old setInterval loops and Matter.js bodies stacking up. I had to build strict teardown functions to wipe the slate clean on every map transition.The game walks through electrostatic desalting, fractional distillation, hydrotreating, catalytic cracking, and gasoline blending (hitting specific Octane and RVP specs).It’s completely free, runs client-side, and has zero ads or sign-ups. I&#x27;d appreciate any feedback on the mechanics, or let me know if you manage to break the physics engine. Happy to answer any questions about the chemical engineering side of things as well.For some reason the URL box is not getting recognized, maybe someone can help me feel less dumb there too. 
<a href="https:&#x2F;&#x2F;fuelingcuriosity.com&#x2F;game" rel="nofollow">https:&#x2F;&#x2F;fuelingcuriosity.com&#x2F;game</a>

Show HN: Vanilla JavaScript refinery simulator built to explain job to my kids

Creator here. Hologram compiles Elixir to JavaScript to run in the browser, enabling full-stack development in pure Elixir - and soon, Local-First applications.This release is a milestone for our porting initiative. 49 contributors ported 150 Erlang functions across 19 modules, pushing client-side Erlang runtime coverage from 34% to 96% and overall Elixir standard library readiness from 74% to 87%.This means the vast majority of Elixir standard library functions needed for full-stack web and basic local-first apps now work in the browser - string processing, collections, sets, binary operations, Unicode normalization, math, time operations, file path handling, and more.Beyond porting, the release includes enhancements, bug fixes, and infrastructure groundwork.Happy to answer any questions!

Hologram v0.7.0: Milestone release for Elixir-to-JavaScript porting initiative

I built this because measuring my age in years felt boring—I wanted to see the kilometers.The first version only used Earth&#x27;s orbital speed (~30km&#x2F;s), but the number moved too slowly. To get the &quot;existential dread&quot; feeling, I switched to using the Milky Way&#x27;s velocity relative to the CMB (~600km&#x2F;s). The math takes some liberties (using scalar sum instead of vector) to make the speed feel &quot;fast,&quot; but it gets the point across.Under the hood, it&#x27;s a single HTML file with zero dependencies. No React, no build step. The main challenge was the canvas starfield—I had to pre-allocate the star objects to stop the garbage collector from causing stutters on mobile.Let me know if the physics makes you angry or if the stars run smooth on your device.

Show HN: I built a space travel calculator using Vanilla JavaScript

Wrote a thing about what makes Elysia stand out in a performance benchmark gameBasically, there&#x27;s a JIT &quot;compiler&quot; embedded into a frameworkThis approach has been used by ajv and TypeBox before for input validation, making it faster than other competitorsElysia basically does the same, but scales that into a full backend frameworkThis gave Elysia an unfair advantage in the performance game, making Elysia the fastest framework on Bun runtime, but also faster than most on Node, Deno, and Cloudflare Worker as well, when using the same underlying HTTP adapterThere is an escape hatch if necessary, but for the past 3 years, there have been no critical reports about the JIT &quot;compiler&quot;What do you think?

Show HN: Elysia JIT "Compiler", why it's one of the fastest JavaScript framework

Hi HN!I&#x27;ve been building this solo for about three and a half years. I kept trying every new project&#x2F;notes tool (Notion, Asana, Trello, etc.) and always ended up back in a plain text file. I wanted something that felt like a text editor on first touch but could grow into real structure when you needed it.<a href="https:&#x2F;&#x2F;lightwave.so" rel="nofollow">https:&#x2F;&#x2F;lightwave.so</a> (desktop only)The tech stack is Laravel, MySQL, Redis, and hand-rolled JavaScript on the client. No frameworks like React&#x2F;Vue&#x2F;etc. ~270 lines of jQuery (out of 80k+ total LOC) for a few legacy DOM utilities, plus IndexedDB for local persistence. Real-time collaboration uses a hybrid approach: HTTP&#x2F;2 POST for resilient ops + WebSockets via Laravel Reverb for live cursors, presence, and edits.This is a pre-release stress test, not a launch. Lightwave will be a paid product. Right now I&#x27;m opening it up because no amount of solo testing replicates getting punched in the mouth by real traffic.The link above has a button to create a test account in 1 click.Known rough edges: the cursor and selection system are built from scratch (like VS Code, not a contenteditable wrapper), so there&#x27;s a lot of surface area. Some keyboard shortcuts may be missing. Desktop only, accessibility not yet implemented. I&#x27;m shipping fixes in real time.There&#x27;s a &quot;Submit Bug or Feedback&quot; button inside the app if something breaks. Happy to answer any questions about the architecture, or anything else.Some highlights:- Paste markdown in, get native blocks. Copy blocks out, get markdown back.- Hierarchical document, structure. Hierarchichal file manager.- Live collab with shared cursors, selection, and presence.- Code blocks with syntax highlighting. LaTeX math blocks.- Full data export: markdown, JSON, and attachments. No lock-in.- Full undo&#x2F;redo with cursor restoration.

Show HN: Lightwave – Real-time notes app, 3.5 years of hand-rolled JavaScript

Hi HN, I&#x27;ve been building Mystral Native — a lightweight native runtime that lets you write games in JavaScript&#x2F;TypeScript using standard Web APIs (WebGPU, Canvas 2D, Web Audio, fetch) and run them as standalone desktop apps. Think &quot;Electron for games&quot; but without Chromium. Or a JS runtime like Node, Deno, or Bun but optimized for WebGPU (and bundling a window &#x2F; event system using SDL3).Why: I originally started by starting a new game engine in WebGPU, and I loved the iteration loop of writing Typescript &amp; instantly seeing the changes in the browser with hot reloading. After getting something working and shipping a demo, I realized that shipping a whole browser doesn&#x27;t really work if I also want the same codebase to work on mobile. Sure, I could use a webview, but that&#x27;s not always a good or consistent experience for users - there are nuances with Safari on iOS supporting WebGPU, but not the same features that Chrome does on desktop. What I really wanted was a WebGPU runtime that is consistent &amp; works on any platform. I was inspired by deno&#x27;s --unsafe-webgpu flag, but I realized that deno probably wouldn&#x27;t be a good fit long term because it doesn&#x27;t support iOS or Android &amp; doesn&#x27;t bundle a window &#x2F; event system (they have &quot;bring your own window&quot;, but that means writing a lot of custom code for events, dealing with windowing, not to mention more specific things like implementing a WebAudio shim, etc.). So that got me down the path of building a native runtime specifically for games &amp; that&#x27;s Mystral Native.So now with Mystral Native, I can have the same developer experience (write JS, use shaders in WGSL, call requestAnimationFrame) but get a real native binary I can ship to players on any platform without requiring a webview or a browser. No 200MB Chromium runtime, no CEF overhead, just the game code and a ~25MB runtime.What it does:
- Full WebGPU via Dawn (Chrome&#x27;s implementation) or wgpu-native (Rust)
- Native window &amp; events via SDL3
- Canvas 2D support (Skia), Web Audio (SDL3), fetch (file&#x2F;http&#x2F;https)
- V8 for JS (same engine as Chrome&#x2F;Node), also supports QuickJS and JSC
- ES modules, TypeScript via SWC
- Compile to single binary (think &quot;pkg&quot;): `mystral compile game.js --include assets -o my-game`
- macOS .app bundles with code signing, Linux&#x2F;Windows standalone executables
- Embedding API for iOS and Android (JSC&#x2F;QuickJS + wgpu-native)It&#x27;s early alpha — the core rendering path works well &amp; I&#x27;ve tested on Mac, Linux (Ubuntu 24.04), and Windows 11, and some custom builds for iOS &amp; Android to validate that they can work, but there&#x27;s plenty to improve. Would love to get some feedback and see where it can go!MIT licensed.Repo: <a href="https:&#x2F;&#x2F;github.com&#x2F;mystralengine&#x2F;mystralnative" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;mystralengine&#x2F;mystralnative</a>Docs: <a href="https:&#x2F;&#x2F;mystralengine.github.io&#x2F;mystralnative&#x2F;" rel="nofollow">https:&#x2F;&#x2F;mystralengine.github.io&#x2F;mystralnative&#x2F;</a>

Show HN: Mystral Native – Run JavaScript games natively with WebGPU (no browser)

JavaScript DRMs Are Stupid and Useless

HDRify: True HDR image viewer, and tool set in pure JavaScript

Flappy Bird Made in Pure HTML and CSS – Without JavaScript

Hologram v0.8.0: Elixir Gets JavaScript Interop

Six JavaScript zero-day bugs lead to fears of supply chain attack

I wanted something lighter than zig autodoc so I&#x27;ve implemented (and golfed a bit) a custom parser using parser combinators in JS. It&#x27;s not 100% correct and it&#x27;s also not meant to be, all I care about is if it can parse my own Zig code, not any valid Zig code.There are also some bugs, and I don&#x27;t intend to support, nor develop this much further, consider it vaporware which you are free to fork and use it for something, or just have some fun reading the code and figuring out how it works (I certainly had a lot of fun implementing it - no LLMs, so it was a nice exercise too).BTW: I know it&#x27;s probably very inefficient, and I don&#x27;t care - it goes through 67 files in 0.19s and I don&#x27;t expect it to be ever a bottleneck for this use-case, so I&#x27;ve spent exactly 0 minutes trying to optimize it.

Show HN: Zig parser in ~70 lines of JavaScript

I’ve been working on MicroState, a city builder prototype written entirely in vanilla JavaScript using the HTML5 2D Canvas API.My goal was to see how far I could get with a 2.5D isometric style simulation with vanilla JavaScript built very simply and drawn entirely with procedural generation for maps, tiles, roads, trees, buildings, etc.The most interesting element is probably the terrain model, which allows for fairly arbitrary terrain.Although some of the generated graphics like trees are cached as sprites, buildings- which are much more intensive to draw - are not cached yet, and many will probably cause your CPU fan to go brrr.It&#x27;s not quite a game yet, though it is &quot;playable&quot; and I thought folks might find it fun to try and have suggestions for features and gameplay they&#x27;d like to see, both in single player and multiplayer.I&#x27;ll be publishing the source on GitHub soon so it&#x27;s easier to submit and track features and defects (and to clone and fork).Happy to answer any questions!

Show HN: MicroState – JavaScript City Builder

JavaScript powers the web - it's **the** most important programming language you need to know as a web developer.

## Exempel 1

For example, We have an array of different objects that can weigh the same or different and are spaced apart from us.
The customer wants the lightest and closest object.

```js
object.sort((a,b)=>a.weigh - b.weigh)

 const lightest=(object[0].weigh);
 let sortDistance=(object[0].distance); 

 for (let i = 0; i< object.length; i++) { 
 if (lightest === object[i].weigh && sortDistance > object[i].distance){
 sortDistance = object[i].distance;
 sortObject.unshift(object[i]);
 }else{
 sortObject.push(object[i]);
 }
 }
```

... more comming soon

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