Replacing JavaScript with Just HTML

JavaScript Demos in 140 Characters

I ported JustHTML from Python to JavaScript with Codex CLI and GPT-5.2 in hours

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

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Hi HN!I&#x27;m building a JavaScript debugger called Wirebrowser. It combines network inspection, request rewriting, heap snapshots, and live object search.The main experimental feature is BDHS (Breakpoint-Driven Heap Search): it hooks into the JavaScript debugger and automatically captures a heap snapshot at every pause and performs a targeted search for the value or structure of interest.
This reveals the moment a value appears in memory and the user-land function responsible for creating it.Another interesting feature is the Live Object Search: it inspects runtime objects (not just snapshots), supports regex and object similarity, and lets you patch objects directly at runtime.Whitepaper:
<a href="https:&#x2F;&#x2F;fcavallarin.github.io&#x2F;wirebrowser&#x2F;BDHS-Origin-Trace" rel="nofollow">https:&#x2F;&#x2F;fcavallarin.github.io&#x2F;wirebrowser&#x2F;BDHS-Origin-Trace</a>Feedback very welcome, especially on whether BDHS would help your debugging workflow.

Show HN: Wirebrowser – A JavaScript debugger with breakpoint-driven heap search

JavaScript's For-Of Loops Are Fast

The Performance Revolution in JavaScript Tooling

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

Hi HN,I built Titan, a backend framework where you write routes and logic in JavaScript, and the CLI compiles everything into a single Rust + Axum binary using the Boa JS engine. No Node.js is required in production.The idea is to keep JS developer experience while getting Rust performance and a self-contained deployable server.Current features:JS route DSLAction system mapped to Rustesbuild bundlingGenerated Rust server with AxumHot-reload dev serverSingle-binary outputRepo: <a href="https:&#x2F;&#x2F;github.com&#x2F;ezet-galaxy&#x2F;-ezetgalaxy-titan" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;ezet-galaxy&#x2F;-ezetgalaxy-titan</a>Would love feedback on the architecture, DX, and whether this hybrid JS→Rust approach is useful.Thanks for reading!

Show HN: Titan – JavaScript-first framework that compiles into a Rust server

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)

Why Object of Arrays beat interleaved arrays: a JavaScript performance issue

I’ve spent a decade doing frontend work. It pays pretty well but I am essentially just making modals and dropdowns for CRUD apps. I crave more purpose in life but understand the most rational choice is to keep going and saving for retirement.Does it make sense to change direction at this point? I envy PhDs working on self-driving cars and rockets and AI. But also question overall morality of the tech industry.

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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]);
 }
 }
```

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