标签：#react

Prologue A while ago, I decided to develop a fully accessible main navigation component in React and write a series of articles documenting the steps it took to create a non-trivial accessible component. This article completes the process of creating a main navigation component that is universally accessible, both perceptually and operatively; can operate in a controlled or uncontrolled state; and is operable when displayed in a horizontal, desktop arrangement as well as in a vertical, mobile scenario. Note : This article is one of a series demonstrating building a React navigational component from scratch while considering accessibility through the process. The articles are accompanied by a GitHub repository with releases tied to one or more articles; each builds on the previous one until a fully implemented navigation component is complete. Each release and its associated tag contain fully runnable code for the article. The code discussed in this article is available in the release. and may be downloaded at release 1.0.0 . Links in the article will take you to the proper file in the tagged GitHub Repository. Because the code for this release is scattered across components, line numbers are added to make it easier to locate in the linked GitHub file. Line numbers are also provided for those who would like to follow along with a downloaded copy. While code examples are written in JavaScript for brevity, all actual code is written in Typescript and targets React 19.x, all while using vanilla CSS. Examples use Next.js v16.x, which is not required to run the navigation component. You can view the requirements for Vertical Alignment along with previous requirements. Content Links Introduction Acceptance Criteria Data Setup Keeping SubLists Open Allowing Scroll when Focus Shifts Down Arrow Key Implementation Up Arrow Key Implementation Conclusion Introduction Up until now, all keyboard handling has been implemented with the default horizontal layout in mind. When display

React useIntersectionObserver Hook: Lazy Load & Detect Visibility (2026) You want to load an image only when it scrolls near the viewport. Or fire an analytics event the first time a card is actually seen . Or trigger "load more" when the user reaches the bottom of a list. Every one of these is the same question — is this element on screen yet? — and for years the answer was a scroll listener that fired hundreds of times a second, re-read getBoundingClientRect() on each tick, and still managed to miss the edge cases. IntersectionObserver is the browser API that answers that question correctly, asynchronously, and off the main thread. useIntersectionObserver is the hook that wires it into React without the useEffect / useRef /cleanup boilerplate — and without the leak-on-unmount and stale-closure bugs the hand-rolled version always ships. This post covers the real @reactuses/core API, the three patterns you'll actually reach for, and how to tune threshold , rootMargin , and root . SSR-safe and typed. Why Not Just Use a Scroll Listener? The old way to know whether an element was visible looked like this: listen to scroll , and on every event measure the element against the viewport. useEffect (() => { function onScroll () { const rect = el . getBoundingClientRect (); if ( rect . top < window . innerHeight ) { setVisible ( true ); } } window . addEventListener ( ' scroll ' , onScroll ); return () => window . removeEventListener ( ' scroll ' , onScroll ); }, []); This has two problems baked in. First, scroll fires on the main thread, dozens of times per second, and getBoundingClientRect() forces a synchronous layout each time — that's exactly the recipe for janky scrolling. Second, it only catches elements crossing the viewport ; the moment your scroll happens inside a container, you're re-deriving geometry by hand. IntersectionObserver flips the model. You hand the browser a target and a threshold, and it tells you — asynchronously, batched, off the scroll path — when

i did something dumb last month. on purpose. i sat down, opened a next.js app, and tried to make hydration fail in every way i could think of. not because a bug forced me to. not because i was debugging something. just because i wanted to see it. understand it from the inside. and honestly? best few hours i've spent learning anything in a while. why i even did this you know how you use something for months and you think you get it, but you don't really get it? hydration was that for me. i knew the surface-level thing: server renders HTML, client takes over, they gotta match. cool. got it. moving on. except i didn't get it. i just got the vibe of it. every time i saw hydration mismatch, i'd ask claude, fix the immediate thing, feel vaguely annoyed, and move on. i never stopped to ask why that specific thing broke it. i was treating symptoms, not understanding the actual disease. so i decided to break it deliberately. if i caused the errors myself, i'd actually have to understand what i was doing. the setup basic next.js app. app router. a few pages. nothing fancy. i wasn't trying to build anything. i was trying to destroy something, carefully, so i could see what fell apart and why. break #1: the obvious one - new Date() on render this is the classic. everyone's seen it. export default function Page () { return < div > { new Date (). toLocaleString () } </ div > } server renders this at, say, 14:00:00. by the time react runs on the client and tries to reconcile, it's 14:00:01. the strings don't match. react screams. thing is, i knew this would happen. what i didn't think about was why react cares. here's the thing: react isn't doing a full diff on the entire DOM after hydration. it's trusting that the server HTML is a valid starting point and it's just attaching event listeners and state to it. but if the content doesn't match, it doesn't know what to trust. it can't partially hydrate "mostly correct" HTML. it either matches or it doesn't. so it throws the warning, a

Let’s be honest: as developers, our relationship with our office chairs is... complicated. We start the day sitting upright like productivity gurus, but four hours into a debugging session, we’ve morphed into a human pretzel. This "gamer lean" isn't just a meme; it leads to chronic back pain and decreased focus. In this tutorial, we are going to build a real-time posture tracking system using MediaPipe Pose and Computer Vision to save your spine. By leveraging AI productivity tools and the power of cross-platform Electron desktop apps , we will create a silent guardian that watches your form and pings you the moment you start slouching. If you've been looking for a practical way to dive into MediaPipe and Node.js integration, you're in the right place. For those looking for more production-ready patterns and advanced AI implementations, I highly recommend checking out the deep dives at WellAlly Blog . 🏗 The Architecture The system works by capturing frames from your webcam, processing them through a pre-trained neural network to identify body landmarks, and then applying some basic trigonometry to determine if your posture is healthy. graph TD A[Webcam Stream] --> B[MediaPipe Pose Engine] B --> C[Extract 33 Keypoints] C --> D{Geometry Engine} D -->|Angle > Threshold| E[Slouch Detected] D -->|Angle < Threshold| F[Good Posture] E --> G[Electron Main Process] G --> H[System Notification 🔔] F --> I[Wait 5s] I --> A 🛠 Prerequisites To follow along, you'll need: Node.js (v16+) MediaPipe (The pose solution) OpenCV.js (For frame manipulation) Electron (For the desktop shell) 🚀 Step 1: Setting Up the Pose Engine MediaPipe provides a "Pose" model that gives us 33 landmarks in 3D space. For posture correction, we specifically care about the Ears (7, 8) , Shoulders (11, 12) , and Hips (23, 24) . The Math: Calculating the "Slouch" We measure the angle between the Ear, the Shoulder, and a vertical axis. If your ear moves too far forward relative to your shoulder, that's "Forward

Today, we’re excited to launch UIAble v1.0, an open-source component library built for developers, by developers. We explored a lot of UI libraries built on Shadcn. Most of them feel nearly identical — same structure, same aesthetic, same tradeoffs. That’s what pushed us to build something different. Not another library that looks like Shadcn with a coat of paint, but a design system with its own identity and a clearer sense of what it’s actually for. Why UIAble exists After enough frontend projects, one thing becomes obvious: the same UI patterns get rebuilt again and again. Inputs. Dialogs. Tables. Alerts. Dropdowns. OTP fields. Form validation states. Not because they’re hard to build, but because most existing libraries never quite fit real project requirements. Some are too opinionated. Some pile on unnecessary abstraction. Some become rigid after initial setup. And some make simple UI unnecessarily complicated. That friction is what led to UIAble. Not to launch another oversized library, just to build a cleaner, more practical foundation for modern frontend development. What UIAble actually is UIAble is a free, open-source UI component library built with Tailwind CSS , Shadcn-style architecture , and Base UI principles . The idea is straightforward: reusable components should stay flexible, readable, and easy to maintain. Instead of pulling projects into a rigid ecosystem, UIAble gives you components you can copy directly into your codebase, edit freely, and scale without fighting the library. No lock-in. No unnecessary abstraction. No dependency trap. What makes it different in practice A few things actually matter here. You get the code. UIAble doesn’t hide logic behind layers of packaging. You see the component. You edit it. You ship it. That alone changes how teams work with UI. It’s built for real product UI, not showcase pages. A lot of UI kits look great in demos and fall apart in production. UIAble focuses on the unglamorous stuff, forms that don’t bre

Comparing the most feature-rich React data grids in 2026, from pivot tables and tree data to...

In the world of wearable health technology, the holy grail has always been moving intelligence from the cloud to the edge. Waiting for a cloud server to analyze your heart rhythm is not just a latency issue—it's a privacy and battery life concern. Today, we are diving deep into TinyML , Edge AI , and ECG signal processing to build a real-time abnormality detector. By leveraging TensorFlow Lite for Microcontrollers and the versatile ESP32 , we can process raw electrocardiogram (ECG) data locally. This approach ensures low-latency detection of arrhythmias while keeping sensitive medical data on-device. If you've been looking to bridge the gap between high-level deep learning and low-level embedded systems, you're in the right place! The Architecture: From Raw Signal to Insight 🏗️ The pipeline involves capturing a high-frequency analog signal, cleaning it, and feeding it into a quantized Convolutional Neural Network (CNN). Here is how the data flows through our ESP32: graph TD A[Raw ECG Signal/Sensor] -->|ADC Sampling| B(Preprocessing: Bandpass Filter) B --> C{Buffer Management} C -->|Windowed Segment| D[TFLite Micro Inference Engine] D --> E{CNN Model Classification} E -->|Normal| F[Log: Sinus Rhythm] E -->|Abnormal| G[Trigger Alert: Arrhythmia] G -->|Bluetooth/Wi-Fi| H[Mobile Dashboard] Prerequisites 🛠️ To follow this advanced guide, you'll need: Hardware : ESP32 (DevKit V1 or similar). Sensor : AD8232 ECG Module (or simulated ECG data). Software : Arduino IDE or PlatformIO. Frameworks : TensorFlow Lite for Microcontrollers (TFLM), EloquentTinyML (optional wrapper), or the standard C++ TFLM library. Step 1: Model Training & Quantization 🧠 Before we touch the C++ code, we need a model. Typically, we use the MIT-BIH Arrhythmia Database to train a 1D-CNN. The crucial step is Post-Training Quantization . Since the ESP32 doesn't have a dedicated NPU, we convert our 32-bit float model into an 8-bit integer (INT8) model. This reduces the size by 4x and speeds up inference s

We've all been here. A new form shows up, you install React Hook Form, add Zod or Yup, and in ten minutes you have something that "works." The problem doesn't surface that day. It surfaces three months later, when the same VIN you validate in the create car form also has to be validated in edit , in import from Excel , and it turns out the rule —"17 characters, the last 5 numeric"— is written three times, each one slightly different, and none of them lives in a place you can point to and say "here is what a valid VIN is." A typical form with a library looks roughly like this: const schema = z . object ({ vin : z . string (). length ( 17 , " The VIN must be 17 characters " ), miles : z . number (). min ( 0 , " Miles cannot be negative " ), // ...and 8 more fields }); const { register , handleSubmit , watch , formState : { errors }, } = useForm ({ resolver : zodResolver ( schema ), }); It works. But if you stop to look at it, you're paying three costs that almost never get named: 1. Clean code dissolves. The business rule ends up scattered across the schema , the resolver , the register calls, the Controller s, and the JSX. The knowledge — what makes a car valid — has no home. It's wired into the UI. And what's wired into the UI doesn't get reused: it gets copied. 2. Performance and coupling are paid silently. These libraries live on subscriptions: watch , re-renders on every keystroke, internal state to keep in sync. For a contact form, who cares. For a screen with 15 fields, sub-forms, and cross-field validation, your component is tied to the library's lifecycle —not yours— and you start fighting it instead of using it. 3. Developer convenience is a trap. It's wonderfully convenient at first . But that same rule: how do you test it without mounting a component? How do you move it to the backend? How do you translate it into two languages without polluting the schema? Everything the library gave you for free, it charges you for the day you need to step outside its mo

"Prop drilling is bad, use Context" is repeated everywhere — but the actual cost stays abstract. So I put the two approaches side by side with live render counters. Click one button and the difference is impossible to miss. ▶ Live demo: https://context-vs-props-drilling.vercel.app/ Source (React 19 + TS): https://github.com/dev48v/context-vs-props-drilling Two identical 4-level trees, both React.memo 'd. One threads a value down as a prop through every level; the other provides it once via Context and reads it only at the leaf. Change the value: Prop drilling → 4 components re-render. Every component on the path receives the changed prop, so all of them re-render — and each intermediate is cluttered with a value it does nothing with except pass along. Context → 1 component re-renders. The intermediates take no value prop, so they're skipped (memoized, props unchanged). Only the consumer leaf re-renders. The summary tallies it on every click: 4 vs 1 . Why Context skips the middle This is the part that surprises people: with Context, an intermediate component can be skipped even though a descendant re-renders . < ThemeCtx . Provider value = { val } > < A /> { /* memo, no props → skipped on value change */ } </ ThemeCtx . Provider > const A = memo (() => < B />); // skipped const B = memo (() => < C />); // skipped const C = memo (() => < Leaf />); // skipped const Leaf = () => { const value = useContext ( ThemeCtx ); // ← re-renders on context change return < div > { value } </ div >; }; React re-renders context consumers directly when the provider value changes — it doesn't need to re-render the components in between. With prop drilling there's no such shortcut: the only way the value reaches the leaf is through every parent, so every parent must re-render. The catch — Context isn't a free lunch Context isn't a "no re-renders" button. Every consumer re-renders whenever the provider value changes — there's no built-in selective subscription. One big, chatty context ca

You know the drill. You build a beautiful set of shadcn/ui components for Project A — a Button, a Card, a Dialog with custom animations. Then Project B kicks off. You copy the files over. Then Project C. Then a subtle bug is found in the Button. Now you're patching it in three places. This is the classic monorepo problem, and it's exactly what I set out to fix. What I Built turborepo-react-shadcn-starter is a production-ready monorepo template that wires up: Turborepo for workspace orchestration and intelligent build caching React + Vite for the fastest possible frontend dev experience shadcn/ui as a shared package — write once, use everywhere TypeScript across the entire workspace ESLint with shared config baked in The key insight: shadcn/ui lives in @repo/ui , a shared package, not inside any single app. Every app in your monorepo consumes the same components from the same source of truth. The Problem with Typical Setups Most teams drop shadcn/ui directly into a single app. That works fine until you need a second app. Then your choices are: Copy-paste the components → drift and duplication immediately Publish to npm → versioning overhead for internal code Monorepo with a shared package → ✅ This is the right answer Turborepo makes option 3 near-effortless, but setting it up from scratch (workspace configs, TypeScript path aliases, ESLint sharing, shadcn CLI pointing at the right package) takes a few hours of trial and error. This starter eliminates all of that. What's Inside turborepo-react-shadcn-starter/ ├── apps/ │ └── web/ # Vite + React app ├── packages/ │ ├── ui/ # @repo/ui — shared shadcn/ui components │ ├── eslint-config/ # @repo/eslint-config │ └── typescript-config/ # @repo/typescript-config ├── turbo.json └── package.json apps/web — The Main App A clean Vite + React app already wired to consume components from @repo/ui . No boilerplate to delete, no config to untangle. packages/ui — The Shared Component Library This is where all your shadcn/ui components

Headline: The wins come from context, not cleverness. An AI with your codebase, your design system, and your deploy logs in scope writes code that ships. Without that scope, it writes plausible code that doesn't. Two years ago, AI coding tools were autocomplete with attitude. In 2026 they are a credible second engineer — provided you build the workflow around them. This is the workflow I run today at Devya Solutions and on personal projects like eng-ahmed.com . The Stack Claude Code in the terminal — long-horizon, multi-file edits with skills and subagents. MCP (Model Context Protocol) servers for live access to docs, deployments, browser, and design tools. Cursor or VS Code for inline edits when I want to stay in the IDE. Why Context Is Everything The single highest-leverage move in AI-assisted dev is feeding the model the right context. MCP servers do this without prompt stuffing. Docs MCP — pulls current library docs at call time, so the model doesn't hallucinate the Tailwind v3 API in a v4 codebase. Browser MCP (Claude-in-Chrome) — lets the agent open the running dev server, screenshot the page, and verify the change actually rendered. Vercel MCP — fetches deploy logs and runtime errors directly. No more pasting logs. Context-mode MCP — keeps file scans, search results, and command output in a sandbox, only surfacing what's relevant to your conversation. A Real Workflow The blog page redesign I just shipped was built in a single 45-minute session. Rough flow: State the goal — two sentences, not a spec doc. Let the agent scout — Claude Code greps, reads a few files, proposes a plan. Iterate visually — screenshot the result, feed it back. The agent fixes the sticky-filter scroll bug in one turn. Commit and push — a single cm shortcut runs build, commits, and pushes. Vercel deploys on push. What the Agent Is Still Bad At Holistic taste — it copies the closest example in your codebase. If that's mediocre, the new feature is mediocre. Domain knowledge — it doesn't kn

React dialogs often start simple. You add an isOpen state, then a selected item state, then confirm/cancel callbacks, then another dialog after the first one. Eventually, a simple flow can become scattered across multiple components. For example, a user flow like this: Select a user Confirm the action Add the user often becomes multiple pieces of state: const [ isUserSearchOpen , setIsUserSearchOpen ] = useState ( false ); const [ isConfirmOpen , setIsConfirmOpen ] = useState ( false ); const [ selectedUser , setSelectedUser ] = useState < User | null > ( null ); This works, but the actual flow is harder to read. What if dialogs could be handled as async flows? I wanted the code to read closer to the user flow: const user = await openAsync ( UserSearchDialog ); if ( ! user ) return ; const confirmed = await openAsync ( ConfirmDialog , { title : `Add ${ user . name } ?` , }); if ( confirmed ) { await addUser ( user . id ); } The dialog opens, waits for a result, and the caller continues based on that result. This is about orchestration, not UI This is not meant to replace Radix, MUI, Headless UI, shadcn/ui, or custom dialog components. Those libraries solve the dialog UI problem well. The idea here is to manage the flow around dialogs: opening dialogs from anywhere under a provider resolving typed result values handling nested dialogs distinguishing completed vs dismissed supporting dismissal reasons guarding close behavior with shouldClose So the actual dialog UI can still be your own component. I packaged the pattern I turned this idea into a small open-source library called react-dialog-flow . It provides a headless dialog stack, Promise-based openAsync , typed results, nested dialogs, closeTop , closeAll , dismissal reasons, shouldClose , and optional UI primitives. GitHub: https://github.com/CHOKANGYEOL/react-dialog-flow npm: https://www.npmjs.com/package/react-dialog-flow Docs: https://dialog-flow.kangyeol.com/ It is still early, so I am mainly looking for feed

We tend to write React as functional programming because the functional component is the mainstream. In this era, one of the issues we often encounter is conditional statements. There are a variety of conditional statements, such as if, switch, and ternary operator. We confuse when to use them properly. Assign the result of the conditional statement into a variable This makes it easy to read, test, and modify codebases. The representative case is ternary operator const userName = user ? user . name : ' No user found ' ; Of course, we can write the code another way. const point = 80 ; let result ; if ( point >= 70 ) { result = ' passed ' ; } else { result = ' failed ' ; } console . log ( result ); // passed In this way, we can not ensure the immutability of let , and this section with the conditional branch is written in a procedural style. To solve this issue, we have to wrap this in a function. const judge = ( point : number ) => { if ( point >= 70 ) { return ' passed ' ; } return ' failed ' ; }; In addition to wrapping that statement, I suggest that you use early return to save the else statement. Do not write conditional statements in the return value of tsx (the UI rendering portion) ** When there is only a single conditional statement, or there is no need for any execution in the conditional statement. Let's use the ternary operation simply. import { FC } from ' react ' ; import { useQuery } from ' @tanstack/react-query ' ; import getUser from ' domains/getUser ' ; type Props = { userId : number ; }; const Profile : FC < Props > = ( props ) => { const { userId } = props ; const getSpecificUser = async () => { const specificUser = await getUser ( userId ); return specificUser ; }; const { data : user } = useQuery ([ ' user ' , userId ], getSpecificUser ); const userName = user ? user . name : ' User not found ' ; return < p > User ： { userName } < /p> ; }; export default Profile ; const userName = user ? user . name : ' User not found ' ; In this statement, you

Prologue A while ago, I decided to develop a fully accessible main navigation component in React and write a series of articles documenting the steps it took to create a non-trivial accessible component. In my last development article , I finally completed the requirements for delivering an uncontrolled navigation component with a horizontal layout; with full keyboard functionality, along with adding the niceties of closing sublists when lists are closed and making sure any open sublist on the top row closes when focus shifts away from it. Rather than write an entirely new component for a mobile version, I'm going to modify the existing code. This first article outlines the steps necessary to set up and work with a controlled component. -— Note : This article is one of a series demonstrating building a React navigational component from scratch while considering accessibility through the process. The articles are accompanied by a GitHub repository with releases tied to one or more articles; each builds on the previous one until a fully implemented navigation component is complete. Each release and its associated tag contain fully runnable code for the article. The code discussed in this article is available in the release. and may be downloaded at release 1.0.0 . Links in the article will take you to the proper file in the tagged GitHub Repository. Because the code for this release is scattered across components, line numbers are added to make it easier to locate in the linked GitHub file. Line numbers are also provided for those who would like to follow along with a downloaded copy. While code examples are written in JavaScript for brevity, all actual code is written in Typescript and targets React 19.x, all while using vanilla CSS. Examples use Next.js v16.x, which is not required to run the navigation component. You can view the requirements for the Controlled Components Release along with previous requirements. Content Links Introduction Acceptance Criteria Contr

You added a useLayoutEffect to measure a tooltip, shipped it, and the next time your Next.js (or Remix, or Gatsby) dev server rendered a page on the server, the console lit up: Warning: useLayoutEffect does nothing on the server, because its effect cannot be encoded into the server renderer's output format. This will lead to a mismatch between the initial, non-hydrated UI and the intended UI. To avoid this, useLayoutEffect should only be used in components that render exclusively on the client. The warning is correct, the suggested fix ("only use it on the client") is unhelpful, and the obvious workaround — just switch to useEffect — quietly reintroduces the visual bug you used useLayoutEffect to kill in the first place. useIsomorphicLayoutEffect is the small hook that resolves the standoff. This post explains exactly why the warning happens, why the two naive fixes are both wrong, and what the one-line hook actually does. Why useLayoutEffect Exists At All React gives you two effect hooks that look nearly identical: useEffect runs after the browser has painted. Its callback is queued and fires asynchronously once the frame is on screen. useLayoutEffect runs before the browser paints, synchronously, right after React has mutated the DOM but before the user sees anything. That timing difference is the whole point. If you need to read layout — getBoundingClientRect , scrollHeight , the measured width of a node — and then write a style based on it, you have to do it before paint. Otherwise the user sees one frame of the wrong layout, then a flicker as your useEffect corrects it. The canonical example is a tooltip that has to position itself relative to its own measured size: function Tooltip ({ targetRect , children }) { const ref = useRef < HTMLDivElement > ( null ); const [ pos , setPos ] = useState ({ top : 0 , left : 0 }); useLayoutEffect (() => { const { height , width } = ref . current ! . getBoundingClientRect (); // place the tooltip above the target, centered s

This is the public, sanitized version of an internal proposal I wrote to move our production app off Next.js. Next.js is the default answer to "I want to build a React app." It's a great framework. But default and necessary aren't the same word. The gap between them quietly cost us speed, debuggability, and a surprising amount of cross-team friction. We were building an authenticated, data-heavy product: dashboards, filters, charts. Almost every screen lived behind a login and updated in response to clicks. For that shape of app, server-side rendering wasn't buying us much, and it was charging us a lot. First, the only question that matters The right architecture depends on what you're building. Content-first: Marketing sites, blogs, storefronts, docs. Mostly public, SEO matters, lots of static content. SSR/SSG is a genuinely great fit. Use Next.js. Seriously. Application-first: Internal tools, dashboards, admin panels, SaaS consoles. Behind auth, highly interactive, bottlenecked by your API and DB — not by React rendering. Put an application-first product on a content-first framework and you pay for machinery you never use. That was us. What SSR actually cost us Production debugging got harder Server-rendered errors don't map cleanly to the components you wrote, so root-causing took longer every single time. Client-side, the error happens in the browser with a stack trace that points at your component. Boring and fast to fix. Server components fought our tests You can't cleanly unit test a server component that renders other server components. Tools like React Testing Library expect renderable elements, not the serialized output a server component produces. We ended up making design choices purely to stay testable. Tail wagging the dog. Authentication became a distributed-systems problem This was a big one. If you gate protected pages on the server, the server must read and validate the token on every request, then propagate auth state through hydration. That singl

Model Context Protocol (MCP) is an open standard for connecting AI apps to tools and data sources. A useful way to think about it is as a USB-C port for AI: one standard interface that lets different models plug into different capabilities without custom glue code for every integration. In this project, we combine MCP, Spring AI, and Google Gemini to build a chat app that can answer weather questions using real tools instead of hallucinating. The system has three parts: MCP tool server - a Spring Boot service that exposes weather and geocoding tools AI chat agent - a Spring Boot service that uses Spring AI + Gemini and calls MCP tools when needed React chat UI - a lightweight frontend for sending messages and rendering replies The result is a small but realistic architecture you can extend into a production assistant. Architecture User (Browser:3000) | POST /api/chat v AI Agent (Spring:7171) -- MCP / Streamable HTTP --> MCP Server (Spring:7170) | | | Google Gemini | Bright Sky API (weather) | | OpenStreetMap Nominatim (geocoding) v v Chat response Tool execution The full source code is available on GitHub . 1. The MCP Tool Server The tool server is a Spring Boot application that exposes MCP tools through Spring AI's annotation scanner. It runs on port 7170 and uses Streamable HTTP for transport. Dependencies <dependency> <groupId> org.springframework.ai </groupId> <artifactId> spring-ai-starter-mcp-server-webmvc </artifactId> </dependency> <dependency> <groupId> org.springframework.boot </groupId> <artifactId> spring-boot-starter-web </artifactId> </dependency> Defining tools With Spring AI, a tool is just a Spring bean method annotated with @McpTool : @Component public class WeatherTool { private final WeatherToolService weatherToolService ; public WeatherTool ( WeatherToolService weatherToolService ) { this . weatherToolService = weatherToolService ; } @McpTool ( name = "get_current_weather" , description = "Get current weather by dwd_station_id or by lat/lon" ) p

With the Reactive Data Layer Architecture (RDLA), you establish a clear boundary between public data APIs and private, framework-specific data-source implementations. Your presentation layer operates in a purely reactive manner, observing data changes rather than procedurally querying them. RDLA also simplifies testing by encouraging you to program to interfaces and use clean seeding patterns. By Mervyn Anthony

Note : This article is one of a series demonstrating building a React navigational component from scratch while considering accessibility through the process. The articles are accompanied by a GitHub repository with releases tied to one or more articles; each builds on the previous one until a fully implemented navigation component is complete. Each release and its associated tag contain fully runnable code for the article. The code discussed in this article is available in the release. and may be downloaded at release 0.9.0 . A page showcasing these base components may be run locally through this release. While code examples are written in JavaScript for brevity, all actual code is written in Typescript and targets React 19.x, all while using vanilla CSS. Examples use Next.js v16.x, which is not required to run the navigation component.] The design requirements for this release are available . -— Content Links Introduction Layout Appearance <nav / > Generic Styling Reimagining Focus and Hover Achieving Parity aria-current Refinements Summary Introduction With only one more release coming up and the horizontal layout styling complete, now is the time to focus on completing vertical layout styling. Most of the layout itself was completed in an earlier release and described in the article Laying it all out on the vertical . When styling a component, care must be taken to ensure parity with the information provided by screen readers through some aria attributes. For instance, a navigation component must set the aria-current="page" attribute on a link whose href points to the current page. In the example being shown, the link in question is the "by Era" link, under Find Your Next Story and Tales. ) While screen reader users hear which button or link is the item currently capturing focus, styling is needed to achieve the same for screen users. Visual styling is necessary to guarantee that visual and auditory/tactile users have the same information. Layout @layer system-c

As a systems engineering student and frontend dev, I wanted a portfolio that looked professional without spending days fighting with design. So I built one — and ended up turning it into a reusable template. Here's what I focused on while building it: 1. Customization from a single file The biggest pain with most templates is digging through components to change your info. I put everything — name, bio, projects, skills, social links — into ONE config file. Edit that, and the whole site updates. 2. Light & dark mode Developers love dark mode, so I made it the default, with a smooth toggle for light mode. Both are fully themed. 3. Mobile-first & responsive Most people will view a portfolio on their phone, so I built it mobile-first and tested it down to small screens. 4. Easy deployment It works out of the box with Vercel or any static host, with a beginner-friendly setup guide in the README. The stack React + Vite Tailwind CSS Formspree-ready contact form You can see the live demo here: devfolio-template-vercel-app.vercel.app I also made it available as a template if it's useful to anyone: https://payhip.com/b/t1VUk Would love to hear your feedback — what do you look for in a developer portfolio? react #webdev #tailwindcss #showdev