DEV Community

Moving off Clerk to Better Auth: what's mechanical and what's a rebuild

I've done a fair number of NextAuth to Better Auth moves, and they're mostly mechanical: same general shape, swap the library, fix a few call sites. Clerk is a different animal, and you should know that going in. NextAuth is a library. Clerk is a hosted product: pre-built React components plus a hosted user store that lives on Clerk's servers. When you move off Clerk you're not swapping one auth library for another — you're replacing UI you never wrote, re-implementing session logic Clerk did fo

TypeScriptProgrammingWeb development

12 Oct 2026Save

DEV Community

Percentage Feature Flag Rollout: 100 Stable Cohorts for Import Alerts

TL;DR: Put each tenant into one of 100 deterministic cohorts, then use a backend feature flag to enable silent-import alerts for an increasing percentage of those cohorts. Hash a stable tenant ID plus the flag key and a fixed version, evaluate the flag only when an import is due, and record the decision beside the alert signal. This gives a solo operator one useful control: widen exposure without making the same tenant jump in and out of the alerting cohort. For a B2B SaaS import pipeline, the l

TypeScriptProgramming

11 Oct 2026Save

freeCodeCamp

How to Measure Conformance Between an Operational Specification and Its Execution

In my previous article, I explored executor independence: the idea that different execution mechanisms should be able to satisfy the same operational specification. By executor independence, I mean th

TypeScriptProgrammingDevOps

11 Oct 2026Save

freeCodeCamp

How to Add Structured Data (JSON-LD) to a Next.js Site and Validate It

Structured data has always mattered to search engines. When a search engine reads your page, it sees HTML: a heading, some paragraphs, a date somewhere, a name somewhere else. Structured data tells it

TypeScriptProgrammingSEO

11 Oct 2026Save

DEV Community

3 MCP servers I actually use daily (and how to set them up)

Not a hype list. These are the three MCP servers I have running right now in Claude Desktop. mcp-hub install @modelcontextprotocol/server-filesystem I use this to let Claude read project files directly instead of me copy-pasting code. Configure it to point at your project root. Real usage: "Read the auth module and explain how the token validation works." mcp-hub install @modelcontextprotocol/server-github Lets Claude check issues, read PRs, and browse repos. I use it for code reviews. Real us

TypeScriptProgramming

10 Oct 2026Save

DEV Community

Building a CLI to Generate Versioned Next.js Projects

Starting a new Next.js project often means repeating the same setup: package management, application structure, database integration, authentication, testing, linting, and CI. I wanted a reusable foundation that I could maintain centrally while generating independent projects from known versions. That led me to build create-clubedge-app. The goal was to make starting a project repeatable without turning every generated application into a permanently coupled copy of the starter repository. What t

TypeScriptProgrammingSoftware engineering

9 Oct 2026Save

DEV Community

MCP in 2026: The numbers behind the ecosystem explosion

I spent an afternoon digging through the MCP ecosystem numbers. Here is what I found. 13,000+ MCP servers on npm and GitHub (as of May 2026) 97 million monthly SDK downloads — that is 3x from 6 months ago 400% YoY growth in new server registrations Anthropic official servers reach 48,500 downloads/month for filesystem alone MCP is not just a protocol anymore. It is becoming the standard way to give AI models access to tools — databases, APIs, file systems, everything. But here is the gap: discov

TypeScriptProgramming

9 Oct 2026Save

DEV Community

Building Melody Creator: a Browser-Based Music Sketchpad

Melody Creator is a small browser-based music sketchpad, but the interesting part is not the UI alone. You can try the live tool at melodycreator.app. Under the surface, the app treats melody writing as a set of ordinary engineering problems: model the musical idea, keep generation deterministic, preview sound in the browser, export useful files, and make the result shareable without requiring an account. The project is built with Next.js App Router, React, TypeScript, Tailwind CSS, and a few mu

TypeScriptProgrammingReact

9 Oct 2026Save

DEV Community

Building Type-Safe Biometric Authentication for React Native with Nitro Modules

Biometric authentication has become a standard part of modern mobile applications. Face ID, Touch ID, fingerprint authentication, and device credentials give users a convenient way to verify their identity before accessing sensitive functionality. For React Native applications, implementing these flows still requires communication with native iOS and Android authentication APIs. That was the motivation behind building react-native-nitro-biometrics, an open-source biometric authentication library

TypeScriptProgrammingOpen source

8 Oct 2026Save

DEV Community

Displaying Doors from vPIC Without Inventing Body Marketing Names

NHTSA vPIC often returns a Doors field on DecodeVinValues-style payloads: a short catalog value such as 2, 3, 4, or 5. That number is useful on a free VIN decode card. The trap is turning it into a body marketing name -- "coupe," "hatchback lifestyle," "crew cab luxury" -- that the doors field never asserted. This post is about honest display: show the door count when vPIC provides it, refuse body-style inventing, and allow a clean "not provided" state when the field is empty. Pair Doors with Bo

TypeScriptProgrammingWeb development

7 Oct 2026Save

DEV Community

Model the review step before saving AI output

An AI response can identify a meal and suggest nutrition values. That response still leaves a product decision unresolved: which information does the person want in their diary? If the response is treated as a saved meal immediately, a successful model request can change a daily total before the person has checked the food or portion. A review screen added afterwards cannot restore the distinction the data model has already lost. FoodWarz's domain vocabulary separates an analysis from a meal. An

TypeScriptProgrammingArchitecture

7 Oct 2026Save

DEV Community

Why Your TypeScript Code Still Crashes in Production: Validating Data at Runtime Boundaries with Zod

Mình từng review một incident lúc 2 giờ sáng: service Node.js crash hàng loạt với lỗi TypeError: Cannot read properties of undefined (reading 'toFixed'). Codebase 100% TypeScript, bật strict: true, CI xanh, không có any nào. Vậy mà vẫn sập. Nguyên nhân là bên đối tác đổi field price từ number sang string "12.50", và có record thì trả về null. TypeScript không hề biết chuyện này, vì type chỉ tồn tại lúc compile, còn data thật đến lúc runtime. Bài này chia sẻ cách mình xử lý vấn đề đó trong các dự

TypeScriptProgrammingWeb development

6 Oct 2026Save

DEV Community

We Built a 3D Game Where Your Voice Breaks Reality, As Our Hacker House Submission

"How much of the world are you willing to destroy to create the world you want?" Our team — Alt F4 — built this as our submission for Hacker House Goa 2026 in collaboration with Wispr Flow. And we decided to break every rule we set for ourselves. No game engine. No Unity. No Godot. Just React, TypeScript, Three.js, and a slightly deranged idea: What if your voice was the controller? This is the story of ECHO — a cel-shaded dark fantasy RPG where you speak commands into the browser and the world

TypeScriptProgrammingReact

6 Oct 2026Save

freeCodeCamp

How to Submit a Quarterly Update to HMRC's Making Tax Digital API

Four times a year, every sole trader and landlord in Making Tax Digital (MTD) for Income Tax has to send HMRC a summary of their income and expenses. The first deadline of the 2026-27 tax year, 7 Augu

TypeScriptProgrammingJavaScript

4 Oct 2026Save

freeCodeCamp

How to Separate Operational Intent from the Executor

In my previous article, I argued that software automation needs a layer between operational intent and execution. The reason is simple: the specification should describe what success means, and the ex

TypeScriptProgrammingDevOps

4 Oct 2026Save

Medium

The Breaking Change: Closing a Chapter With Your Head High

Every developer has opened a changelog and felt their stomach drop. Continue reading on Medium »

TypeScriptProgrammingJavaScript

3 Oct 2026Save

DEV Community

Building a Zero-Lag Swiss Tax & Salary Calculator in Next.js (Why We Kept Everything in Browser Memory)

If you’ve ever looked at how taxes and social contributions work in Switzerland, you know it’s notoriously decentralized. There are 26 cantons, each with its own municipal tax multipliers (Steuerfuss), varying church taxes, multiple withholding tax tariffs (Quellensteuer), and statutory pension rules that change based on your exact age bracket. When building LivingSwiss, an expat analytics and financial tool suite, our initial instinct was to treat this like a standard backend system: send the

TypeScriptProgrammingWeb development

2 Oct 2026Save

DEV Community

I Built a Village of Six Agents You Can Actually Inspect

An agent claims a task. Another agent needs the same resources. A third is resting. Who gets the job, and can you explain the decision afterward? That is the kind of question I am exploring with Settlement, a village strategy game and an inspectable simulation lab. With Hacktoberfest focusing on open-source AI this October, it feels like a useful time to share a project where the behavior is visible and the default setup needs no model API key. Choose an objective such as preparing for a raid or

TypeScriptProgrammingAI

1 Oct 2026Save

DEV Community

Design Your Expo Router Tree Before You Write a Single Screen

Most Expo Router tutorials start with npx create-expo-app and a single index.tsx. That's fine for screen one. By screen thirty, the same project usually has three index.tsx files nobody can tell apart, a modal that remounts the whole tab bar, and a components/ folder that accidentally became a set of routes. None of that is a code problem. It's a planning problem. With file-based routing, the folder tree is the navigation design. Every folder you create is a decision about URLs, layouts, and wha

TypeScriptProgramming

1 Oct 2026Save

DEV Community

Realtime Channel and Message Queue Durability for Collaborative Cursor Notifications

A realtime channel makes a collaborative cursor notification immediate; a message queue makes its recovery durable. The awkward constraint is that replaying every old coordinate after a reconnect is usually wrong. The durable thing is not an endless trail of mouse movements. It is the latest useful state, plus enough ordering information to reject stale updates. Short answer: use a realtime channel to accelerate live cursor updates and a durable queue or state log to recover after disconnects. P

TypeScriptProgrammingArchitecture

30 Sept 2026Save

DEV Community

Your Discord bot's member cache is lying to you. Mine never timed out a single member.

I set largeThreshold: 50 in my Discord bot's client config. The comment next to it said it saved memory with no functional loss. That was wrong, and it took a log search to find out how wrong. largeThreshold is the large_threshold field in Discord's gateway IDENTIFY payload. It is the member count above which the gateway stops sending offline members when a guild loads. Above it, a guild counts as "large" and the initial guild payload only carries members who are online. Nothing fills the gap la

TypeScriptProgramming

30 Sept 2026Save

DEV Community

Discord gives your bot exactly 100 slash commands. I hit 100 and found out from a failing test.

Discord limits an app to 100 global slash commands. Subcommands and subcommand groups do not count toward it. My bot, Akiko, sits at exactly 100. I learned where the wall is the hard way. I added a /settings command, the total became 101, and a test failed with expected 101 to be less than or equal to 100. In production the same mistake shows up as Discord error code 30032 when you deploy your commands. There is a test that builds the real list of commands that would be deployed globally and ass

TypeScriptProgramming

30 Sept 2026Save

DEV Community

Preserve First: Recovery Design for Local Creative Data

The most dangerous button in a creative tool is not "delete." It is the recovery dialog that appears when something is already wrong: "We couldn't load your project — start fresh?" One click, and the file that failed to parse at 23:40 is gone at 23:41, together with the chapter it contained. The tool was trying to help. Local-first software cannot afford that. There is no server copy, no support ticket that restores yesterday's state, no account trash bin. When your app is the only place a manus

TypeScriptProgrammingArchitecture

27 Sept 2026Save

DEV Community

React `useActionState` in 2026: Replacing `useReducer` for Server-Driven Form Logic

React useActionState in 2026: Replacing useReducer for Server-Driven Form Logic This article was written with the assistance of AI, under human supervision and review. Most form state management problems stem from mixing client-side validation logic with server response handling. Teams reach for useReducer to coordinate multiple state slices (pending, error, data), then wire up async dispatch patterns that duplicate server-side validation. The result is fragile plumbing where a missing error

TypeScriptProgrammingReact

27 Sept 2026Save

Medium

Zero-Hallucination AI in Node.js

Connecting TypeScript to Neo4j, Memgraph, and FalkorDB Continue reading on Generative AI »

TypeScriptTechnologyAI

25 Sept 2026Save

DEV Community

My AI Agent's Skill Declared Nothing. It Still Read 9 Files, Ran 7 Processes, and Got Blocked 3 Times.

I gave an AI agent a code-review skill. It never mentioned touching the filesystem or spawning processes — just "review this repo." By the time it reported success, it had done both, repeatedly, and hit a policy wall three times along the way. That's when I realized I'd been asking the wrong question about AI agents. How do I know what the agent actually did? Not what it said it did. What did it actually attempt inside the environment? So I designed the approach and prompted Codex to build a har

TypeScriptProgrammingAI

25 Sept 2026Save

DEV Community

How to Build a Task Management App with React & TypeScript

Hey everyone, it's Sadee! If you've ever wanted to build a cool task board where you can move things around—kind of like Trello or Jira—you are in the right place. Today, we are going to build one from scratch. You will be able to click on a task, drag it across your screen, and drop it into a totally new column. The best part? We aren't going to download any heavy drag-and-drop tools. We are just using the native tools that are already built right into your web browser! How We Set Up the Projec

TypeScriptProgrammingWeb development

24 Sept 2026Save

DEV Community

Scoped Permission Error in One Code Branch (Capability Evidence First)

Treat a permission failure on one path as a capability-discovery problem: record the operation that path intends to perform, compare it with the credential's declared grants, and stop before making the outbound call. Rotating the key first can hide the mismatch while quietly widening its blast radius. TL;DR: In a customer-support service, give each workload a narrow credential and a spending boundary. When only the usage-alert path fails, log a stable operation name, the required capability, and

TypeScriptProgrammingCybersecurity

23 Sept 2026Save

DEV Community

The One-Line Refactor That Made this Become undefined in Production

Unlike languages where this is lexically bound to a class instance at definition time, JavaScript decides what this refers to at the moment a function is called, not where it was written. That single distinction has caused more runtime errors than any other keyword in the language. The refactor looked completely safe. A method called updateUser lived on a userStore object, and a component needed to call it in response to a button click. Someone extracted the reference to make the code slightly m

TypeScriptProgrammingJavaScript

23 Sept 2026Save

DEV Community

Stripe said "Cancels". My dashboard said "Renews". The webhook returned 200 the whole time.

I run a small subscription SaaS on Next.js, Drizzle and Postgres, billed through Stripe. Before opening it up to real customers I did the most boring test there is: I became a customer in production. Real card, real trial, real Customer Portal. Then I canceled. Stripe's side looked perfect. The subscription showed a clear "Cancels" badge with the end date. My own dashboard, the page my customers actually look at, still said: Renews on A hard refresh didn't change it. Both webhook deliveries for

TypeScriptProgrammingWeb development

23 Sept 2026Save

DEV Community

Debugging Expo: Fixing Node v18 Incompatibilities and Network ETIMEDOUT Errors on Linux

Setting up a fresh mobile workspace can sometimes feel like running an obstacle course. If you’ve ever run npx create-expo-app only to be met with a wall of engine warnings, random ReferenceError: File is not defined breaks, and persistent ETIMEDOUT network failures, you are not alone. Here is exactly why these errors happen on a Linux environment and a bulletproof roadmap to fixing them. Modern scaffolding tools move fast. The latest editions of create-expo-app heavily leverage modern Web APIs

TypeScriptProgramming

22 Sept 2026Save

Medium

TypeScript Discriminated Unions — The Pattern That Kills Runtime Errors

Stop guessing whether your data exists. Learn how a single TypeScript feature makes impossible application states unrepresentable. Continue reading on Medium »

TypeScriptProgrammingJavaScript

21 Sept 2026Save

DEV Community

Mathematical Formulation of Continuous-Duty Thermal Ampacity in Residential EVSE Systems

Modern residential Level 2 Electric Vehicle Supply Equipment (EVSE) represents the most demanding electrical load ever introduced into standard domestic distribution panels. Unlike traditional household appliances—such as electric ovens, clothes dryers, or central air conditioning compressors that cycle intermittently—an EV onboard charger draws maximum nameplate current continuously for 4 to 12 consecutive hours. Under sustained full-amperage operation, branch circuit conductors and overcurrent

TypeScriptProgrammingWeb development

21 Sept 2026Save

DEV Community

'2026-27' is a better database key than a date range

We sell school and university discounts. A school gets an allocation: a code its students can redeem, capped at some number of redemptions, and the cap resets each year. Each year, but not each calendar year. A sixth form's intake arrives in September. The cohort that used the allocation in the spring has left by the autumn, and resetting their cap on 1 January means resetting it in the middle of application season, which is the worst possible moment for the people relying on it. So the reset is

TypeScriptProgrammingWeb development

21 Sept 2026Save

DEV Community

38 clamps, four probits, and one coefficient rounded to 15 digits

We have around 150 scorers, one per practice game, each converting a finished game state into a score. They live under scoring/scorers/ and were written as self-contained units, which is the right shape: the scoring rules genuinely differ per game, and a shared base class would be a lie about how much they have in common. What they did have in common was arithmetic. Before this cleanup the codebase contained: 38 local definitions of clamp, in three mutually incompatible signatures 10 local mean

TypeScriptProgrammingWeb development

21 Sept 2026Save

DEV Community

Vue `nextTick`: Wait for the DOM to Update Before You Touch It

One of the first things you learn with Vue is that changing reactive state automatically updates the DOM. But there is an important detail that can sometimes cause unexpected behavior: 👉 The DOM doesn't update synchronously after every state change. Vue batches DOM updates and applies them asynchronously. This is an important optimization because multiple state changes can be processed together instead of triggering a separate DOM update for every mutation. Most of the time, you don't need to t

TypeScriptProgrammingJavaScript

21 Sept 2026Save

DEV Community

I built a unique ID generator that's ~60% faster than nanoid

jet-id is a tiny, zero-dependency unique ID generator for JavaScript and TypeScript. IDs are 28-character Crockford base32 strings, with optional timestamps so they sort by creation time. import jetId from 'jet-id'; jetId(); // '9Q8SWWBTY-7NVXM-FT9S6-XB4R3M' jetId.timed(); // '1KKNTQ2CN-606ZG-8VF48-76B6F3' (sorts by creation time) / jet-id jet-id An extremely fast unique ID generator for JavaScript and TypeScript, with optional sorting/timestamping. Quick Gla

TypeScriptProgrammingJavaScript

19 Sept 2026Save

DEV Community

What I Will Not Port While the Rails Move

GitHub: https://github.com/abrownfox0/abrownfox001-twap60-prediction-trigger-system YouTube walkthrough: https://www.youtube.com/watch?v=XzhugRL6BV4 Live profile: https://polymarket.com/@abrownfox001 Part 3 was about making clob.ts boring enough to survive a matching-engine rewrite. Part 4 is the refusal list. Platforms ship surface when rails are unstable. Most of that surface does not belong inside a BTC 5-minute TWAP engine. If it does not help me: pin 60s TWAP enter near 50¢ scratch decay

TypeScriptProgrammingArchitecture

19 Sept 2026Save

DEV Community

A browser arcade in plain TypeScript: 8 classic games, 35 kB, no framework

Play it: https://minjia-hu.github.io/retro-arcade/ https://github.com/Minjia-Hu/retro-arcade A retro-styled collection of browser games. Open the page and play, no install, no sign-up. Snake, Tetris, Breakout, Flappy, 2048, Minesweeper, Sudoku and Gomoku share one arcade-cabinet UI and work with both keyboard and touch. Beyond the basic rules, each game got the things that make you play one more round: Tetris: hold, hard drop, on-screen buttons 2048: single-step undo Sudoku: pencil notes, auto-

TypeScriptProgrammingWeb development

19 Sept 2026Save

Medium

Advanced TypeScript Patterns I Wish I Learned in Year One

Stop fighting the compiler: 6 battle-tested patterns that turn messy codebases into bulletproof systems. Continue reading on Medium »

TypeScriptProgrammingJavaScript

17 Sept 2026Save

DEV Community

React Router Data Mode : Introduction (Part 1)

In this series, I am going to share what I found about React Router!!! React Router is a router for React. Many see it as a simple router for React apps, but I see it as a powerful tool for managing a well-furnished Single Page Application(SPA). Different modes provided by React Router. How declarative mode was lagging. How Data mode introduced in v6 changed everything. How Data mode introduced in v6 changed everything. All utilities and integration. The features available in each mode are addit

TypeScriptProgrammingWeb development

17 Sept 2026Save

Medium

TypeScript Utility Types You Should Be Using Daily

Stop copying and pasting interfaces: write cleaner, bulletproof code with TypeScript’s built-in type transformers. Continue reading on Medium »

TypeScriptProgrammingWeb development

15 Sept 2026Save

Medium

Stop Using ‘any’ in TypeScript — Here’s the Right Fix Every Time

The simple habit that stops runtime bugs before they hit production. Continue reading on Medium »

TypeScriptProgrammingJavaScript

14 Sept 2026Save

DEV Community

Google ADK Callbacks Are a Policy Plane, Not Just Hooks

An agent proposes refund_order. The tool exists, its arguments are valid JSON, and the model sounds confident. None of that answers the question that matters: is this action allowed now? Google's Agent Development Kit gives us interception points before and after agents, models, and tools. The tempting implementation is to add a log statement to each callback. The more useful design is to treat those callbacks as a small policy plane. That does not mean placing every business rule in a callback.

TypeScriptProgrammingAI

14 Sept 2026Save

DEV Community

Why I stopped using heavy UI kits and built a pure Tailwind React 19 dashboard

For years, the standard playbook for scaffolding a React admin dashboard was to install a massive UI library like MUI or AntDesign. It gets you moving fast on day one, but by month three, you are fighting specificity wars, overriding inline styles, and staring at a massive JavaScript bundle. I wanted a clean break from that workflow. I needed an architecture that gave me complete design control without sacrificing performance. So, I built and open-sourced Exo-Dash (available free on GitHub) — a

TypeScriptProgrammingReact

14 Sept 2026Save

DEV Community

A local app cannot keep a secret from its owner, so stop pretending

Our desktop app has a paid upgrade. Somewhere in the code there has to be a boolean that decides whether the feature is on. Here is the comment sitting above it: * Note this is a speed bump, not DRM. A local Electron app cannot keep a secret * from its owner, and this file is plain JSON. Anything that must not be forged * has to be enforced server-side. I want to defend writing that down, because the instinct is to do the opposite — encrypt the file, obfuscate the bundle, add a checksum, mak

TypeScriptProgrammingArchitecture

14 Sept 2026Save

DEV Community

The guard that stops our automation from following a link

Our app can reply to a rental listing for you by replaying a form-filling recipe you recorded once. The most important code in that feature is not the part that fills forms. It is the part that refuses to. Here is the scenario it exists for. You are on a listing on some aggregator. You click "Contact landlord". The aggregator does not have a contact form — it hands you off to a completely different company's site, which asks you to register an account, verify an email, and pay €29.99 for a "prem

TypeScriptProgrammingCybersecurity

14 Sept 2026Save

Medium

TypeScript Generics — The Feature That Makes You a 10x Dev

Stop Copy-Pasting Types and Killing Safety with any — Here’s the Mental Model That Changes Everything Continue reading on Medium »

TypeScriptProgrammingWeb development

13 Sept 2026Save