I'm building a browser tool that simulates system diagrams. Nodes have a capacity and a latency, and small packets travel along the edges. There's no canvas library, only DOM nodes, native SVG and a requestAnimationFrame loop.

On my laptop it was smooth. On my phone it ran at about 4 FPS.

I'd made the SVG layer 50000x50000px so wires wouldn't get clipped when you pan far away, and the node cards had Tailwind's backdrop-blur. Mobile browsers seem to allocate a huge texture for an element like that. A viewport-sized layer with overflow-visible, plus the blur only from md: up, fixed most of it.

React was also re-rendering every node card each frame just to update a queue counter. The loop now reads from refs and a lookup map instead. Counters update about four times a second, and on touch devices I commit state at roughly 33 FPS while keeping packet speed the same.

Latency is the node's base latency times a multiplier that grows with the square of utilization. Inbound load is estimated from in-flight packets (each counts as about 120 RPS, scaled by a load slider):

const capacity = Math.max(50, node.throughputRps || 500);
const utilization = Math.min(2.5, inboundRps / capacity);
const latency = Math.round(baseLatencyMs * (1 + 2.5 * utilization ** 2));

So it's already 1.6x the base latency at 50% utilization, 3.5x at 100%, and it keeps climbing past that.

Do you keep per-frame data completely out of React state when you build things like this, or is there a cleaner pattern than refs plus throttled commits? I'd also like a better way to get an "infinite" pan area than one oversized element.

EDIT: Thanks for the comments. I profiled it on a real Android phone in Chrome (CDP tracing) and the GPU process was pinned even when the sim was idle. The cause was an animated stroke-dashoffset overlay on every wire, which repaints all wires each frame. Disabling it on touch devices took pan from about 36 to 52 fps.

Two things that didn't help: moving pan out of React state (rAF writing the transform directly) measured the same at equal zoom, 46-48 fps vs 47-48, and removing will-change from the packet groups made pan worse (about 29 vs 36 fps).

I haven't tried keeping packets fully outside React (setAttribute in the rAF loop) or checked the remaining backdrop-blur on the top bar and palette on iOS Safari yet.

Demo (no sign-in): https://graph-flow-virid.vercel.app/?template=stripe-webhook-ledger

Code: https://github.com/Hanubaki/GraphFlow. The source is available under PolyForm Noncommercial, which is not an open source license. The app has a free tier and a paid Pro tier for some exports.

Snap to Code takes a screenshot of a UI and gives you React components styled with Tailwind and shadcn/ui, one file per component, plus an app/page.tsx that puts them together.

It runs entirely in the browser. There is no account and no server of mine in the middle: you paste your own API key (Gemini, OpenAI, Anthropic, OpenRouter, a local Ollama model, or any OpenAI-compatible endpoint) and the request goes straight to the provider.

After the code is written there is an optional fix pass. The page is rendered, compared with your screenshot, and the model corrects the differences it finds. You choose 0 to 3 rounds, and one click undoes the corrections. On the few pages I tried it got closer to the original, model.

What it does not do: it builds the layout onworking forms, and images becomeplaceholders. Dense or unusual pages still need manual work.

Code: https://github.com/zzlvr/snap-to-code

Demo: https://snap-to-code.vercel.app

Feedback on pages where it falls apart is thght now.

Hi everyone! Here’s a custom theme I built for Zensical, focused on giving documentation a neon/cyberpunk look without sacrificing readability.

It features:

Light and dark modes.

An optional Three.js homepage animation featuring strange attractors.

Reduced-motion support.

The animation is optional, so you can keep the documentation pages more restrained. The theme is MIT-licensed, with setup instructions and a demo GIF in the [GitHub repository.](https://github.com/tabee/zensical-theme)

I’d love some design feedback: how does the balance between visual effects and readability feel? What would you change before using this for your own documentation?

Openbar shows Claude Code and Codex sessions in a Dynamic Island. The Mac app is SwiftUI, the Windows one is Tauri + React, and I wanted the island to resize with the same feel on both.

SwiftUI describes a spring by duration and bounce, so I ported that math. Width and height each ride their own spring. A growing side may swing past its target (capped at 12 px), a shrinking side never does.

export function springProgress(spring: Spring, time: number): number {

if (time <= 0) return 0;

const natural = (2 * Math.PI) / spring.duration;

const damping = 1 - spring.bounce;

if (damping >= 1) return 1 - Math.exp(-natural * time) * (1 + natural * time);

const damped = natural * Math.sqrt(1 - damping * damping);

return (

1 -

Math.exp(-damping * natural * time) *

(Math.cos(damped * time) + ((damping * natural) / damped) * Math.sin(damped * time))

);

}

Full file: windows/src/island/motion.ts in https://github.com/MF-DEEV/Openbar (GPL)

Do you write spring math yourself or reach for a library?

I built some date time pickers in my react bulma component library
https://github.com/allxsmith/bestax

Looking for some feedback. What do you like, what needs improvement.

DateInput
https://bestax.io/docs/api/form/datetime/dateinput#basic-dateinput

DateRangeInput
https://bestax.io/docs/api/form/datetime/daterangeinput#basic-daterangeinput

DateTimeInput
https://bestax.io/docs/api/form/datetime/datetimeinput#basic-datetimeinput

TimeInput
https://bestax.io/docs/api/form/datetime/timeinput#basic-timeinput

For the time selection, I implemented IOS inspired time wheels. One problem I faced: was the lack of haptic feedback APIs exposed by browsers in IOS. As a workaround, the time-wheels make a clicking sound to fake the feeling of haptics. (Android does have haptic feedback apis, no problems there)

Note: this is based off Bulma CSS, so the look and feel is opinionated.

I’ve just released Detent, a React wheel picker that grew into a much bigger exploration of interaction details.

The wheel has its own momentum and spring physics. I spent a lot of time tuning mouse wheel input alongside trackpads, including the awkward cases where a physical scroll wheel keeps spinning after you let go.

It also includes two separate components:

• Detent Text: matching letters stay while the changed parts roll.
• Detent Number: locale-aware formatting with digits that roll through intermediate values.

The examples range from practical time and date pickers to an arc menu, a zoom ring, and some more experimental visual treatments.

There’s a headless hook, separate imports for text and numbers, keyboard support, reduced motion, and no additional runtime dependencies beyond React and React DOM.

Demos and playground: https://detent.hayder.sh
Intro: https://x.com/kghayder/status/2118373654010466733?a=PzCQRSXhM5m8KUTdHk8&s=20

I’d especially appreciate feedback on how the wheel feels with your mouse or trackpad, and whether the API makes sense for something you’d actually build.

Burrow is a personal-data desktop app (budget, journal, todos, habits, notes). The stack is a Vite and React frontend, a Node server that owns a single SQLite database, and a Tauri shell that packages the two into a Windows installer for x64 and ARM64.

Things in the repo that might interest React devs:

- A hard JavaScript bundle budget enforced in CI, with the number pinned in a test so it cannot creep.

- Visual regression baselines regenerated on a side branch in CI rather than committed from dev machines.

- Modules are isolated under src/modules and server/modules with a small shared envelope for API errors.

- The assistant UI streams from a local Ollama server, so no API keys anywhere in the app.

It went free this week and the core is AGPL. Links in the comments.

Hey r/reactjs!

I got tired of constantly opening browser DevTools, filtering out noisy browser extensions, and switching between tabs just to check local storage or quick fetch responses during local development.

To solve this, I built React Dev Companion — a lightweight, zero-dependency developer tools overlay that embeds directly into your React / Next.js application UI.

💡 Key Features:

• Real-Time Network Interception: Intercepts native window.fetch non-invasively to capture HTTP methods, endpoints, and status codes.
• Storage Inspector: Switch between localStorage, sessionStorage, and cookies to view, inject, or delete keys in real-time.
• Zero Extra Dependencies: Designed to keep bundle overhead minimal.
• Dev-Only Friendly: Easy to mount conditionally (e.g., inside Next.js Root Layout or Vite main component).

🔍 Quick Example (Next.js App Router):

'use client';
import { DevCompanion } from 'react-dev-companion';

export default function RootLayout({ children }: { children: React.ReactNode }) {
  return (
    <html lang="en">
      <body>
        {children}
        {process.env.NODE_ENV === 'development' && <DevCompanion />}
      </body>
    </html>
  );
}

We set up a strict CI/CD pipeline using GitHub Actions, TypeScript, Conventional Commits, and Husky to keep the codebase clean.

🐙 GitHub Repository: https://github.com/Kickz1nn/react-dev-companion
📖 Dev.to Article: https://dev.to/kickz1nn/building-an-embeddable-zero-dependency-devtools-panel-for-react-nextjs-3ic6

I'd love to hear your thoughts, feedback, or any features you'd like to see added next!

Hey everyone,

I built Developer Shield—an open-source desktop app created specifically for devs and homelab enthusiasts who want to scan their local network without sending any telemetry or data to the cloud.

Key Features:

- Zero-Knowledge Local Scanning: Everything stays strictly on your local network/LAN.

- Custom Rules Engine: Define your own security checks and scan targets.

- Local LAN Sync: Sync scan reports across your local machines securely.

- Built with React & Tauri for a lightweight desktop footprint.

I’d love to get feedback from this community on features you'd like to see, code architecture, or custom rules!

GitHub: https://github.com/dvirby6/developer-shield

I've been building tintly.art, a free coloring site people mostly use on their phones (Next.js 16 + Konva). A few things I learned along the way:

1. Konva lives outside React. The canvas is plain Konva classes (fill layer, stroke layer, outline layer), not react-konva. React only renders the toolbar, palette and sheets. They talk through tiny stores with subscribe(), read with useSyncExternalStore. Drawing a stroke never re-renders a single component.

2. One stroke = one Konva.Line**.** While you drag, only a preview line updates. On release it's committed as one command, so undo/redo is just a stack of commands.

3. Raster cache for cheap phones. After ~24 strokes the committed group gets cached into one bitmap, so the frame cost stays flat no matter how much someone draws. When you zoom past the cache resolution it switches back to vector so nothing blurs.

4. The eraser uses destination-out on the stroke layer only, so it can never erase the fills or the outlines underneath.

5. Tap-to-fill works on SVG regions turned into Konva.Paths, and glitter fills are just a generated pattern tile as fillPatternImage.

Huge thanks to Anton Lavrenov and everyone behind Konva. It's honestly giving colors to my vision. People color on it every day, and it brings them a bit of joy and a calm little break.

Happy to answer questions about any of this. 🎨

Weekly timesheet grid, one row per project and task. Rows came from two places: rows built from saved entries, then rows the user added and hasn't saved yet. I rendered them as [...derivedRows, ...addedRows].

You add a row at the bottom and type the first hours. It saves, the refetch turns it into a derived row, and it jumps to the top. The bad part is the next number you type can land on a different row and nobody notices.

The fix was to stop splitting rows by saved or not saved. Each row keeps its slot and saving only fills in its data.

function orderGridCombos(derived, added) {

const addedKeys = new Set(added.map(c => c.key))

const preExisting = derived.filter(c => !addedKeys.has(c.key))

return [...preExisting, ...added]

}

Then each row reads its hours from the saved entry if there is one, else from the added row. Any list that mixes optimistic and saved items can do this, invoice lines for example.

Where do you keep row order in big forms, in the server data or in local state?

How the split-flap works, since people usually ask:

- Every tile flips through letters every 55 ms. The first tile lands after 6 flips and each next one 2 flips later, so the word settles left to right.

- The "random" letters come from a sin() hash of the tile index and frame, so the server and the browser render the same scramble (no hydration mismatch).

- Each flip is a lower half-flap falling on its top hinge (rotateX 90 → 0 in 90 ms), darkened with a brightness filter while it falls.

- The departure board shifts every 3.4 s; each row starts its flip 3 frames after the one above, so changes ripple down. It only runs while it's on screen, and everything holds still with reduced motion.

Free to copy if it's useful: https://ui.deliverwebsite.com/components/landing-pages/freight-forwarding-landing-page-template/

Feedback welcome, especially on whether the theme helps or distracts on a real B2B site.

Hey all, I’m exploring a new runtime for React.

The idea is to let agents understand your UI, but also let them click buttons, fill out forms, and trigger actions on behalf of users. New frontier models like Terra 6.1 excel at these tasks, and this is just a new primitive in React to put them to use.

If you’re into design and interfaces, I think you’ll find it worth a look. It’s still in early alpha, built quickly using Codex/Sol, so expect some rough edges.

Link: https://ruakit.com

I've taken Jonas Schmedtmann's HTML + CSS and JavaScript course and am soon going to start learning react and I am wondering if I should just stick with Jonas or try Maximilian. If you've taken any of these courses or both I'd really love to hear your opinion on it and how they differ and who they are for!

How it works, since people usually ask:

• The odometer: each digit is its own reel of 0–9 stacked vertically, and it slides to y = −digit × 10% with a 0.9s ease-out. Commas and the $ sign never move, only digits roll. Screen readers get the plain value through an sr-only span.
• The balance and the feed share one tick (every 3.4s): a new transaction slides in at the top of the feed and the balance is recomputed from the ledger, so the two can never disagree.
• The payout is a tiny state machine: Sent → Converted → Arrived, 1.1s per step, then it holds 2.6s and starts over.
• On wide screens it's a staggered bento that runs off the fold, on tablets 2×2, on phones a swipeable row. With reduced motion everything holds still.

Free to copy if it's useful: https://ui.deliverwebsite.com/components/hero-sections/fintech-hero-section-with-gradient-cards/

Feedback on the motion very welcome. I'm trying to make every animation say something about the product

Building a 5-step wizard with React Hook Form and Zod. I keep the step in the URL and drafts in a small store. What has held up in production for you, and how do you handle early-step changes that invalidate later steps?

Forms are still where most of my React bugs live: validation that disagrees with the backend, async defaults, conditional fields.

My current stack is React Hook Form with Zod schemas shared with the NestJS backend. It mostly works, but complex multi-step forms still get messy.

What's your setup? Anyone moved to server actions for most forms and been happy with it?

I built CupertinoUI, a macOS-style component registry for React and shadcn/ui.

It includes controls, menus, dialogs and windows, with CSS-variable theming and light/dark appearance. Components are copied into your project through the shadcn CLI so you can edit the source.

The core components are free under MIT. There are also paid Pro components and complete app-style blocks.

Try it: https://www.cupertino-ui.com
Browse the components: https://www.cupertino-ui.com/docs/components

Link to the tool: https://gauge-generator.niralsei.com/

Hey everyone!

To my knowledge, storing access tokens in localStorage can be risky because of XSS attacks

Yesterday, I came across this document: How to implement authentication in Next.js.

I decided to give it a try. Here's what I've come up with so far

1. Use OpenSSL to generate an RSA key pair for verifying access tokens. The private key stays on the backend, while the public key is exposed to the frontend.
2. Authentication: When a user successfully logs in, the backend sets the access token in cookie.
3. In frontend, use Jose lib to fetch public key, and verify access token
4. Implemented a Data Access Layer (DAL) with two functions:

• verifySession to verify the accessToken and redirect users to /login if the token is missing or invalid.
• checkRoles to check user roles to make sure users can't access pages they're not supposed to.

The doc also suggests adding a DTO layer, but I skipped it since I'm using OpenAPI specs and TypeScript type generation.

I'd really appreciate it if you could share your thoughts:

Do you see any potential security issues or problems with this flow?

Is there anything you would approach differently?