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GitHub热门项目 | mailcow: dockerized - 🐮 + 🐋 = 💕 | Stars: 13,228 | 50 stars this week | 语言: JavaScript

Every invoicing tool I tried wanted an account, a subscription, and a copy of my client list on its servers — then charged me monthly to put my own logo on my own invoice. So I built the opposite. Billfold is a complete invoice generator that runs entirely in your browser. No account, no backend, no build step. The whole app is a single index.html file you could email to yourself. It's MIT-licensed and the source is right here: github.com/quantum-hacker0/billfold . Here are the three parts that were actually fun to build. 1. "No server" isn't a privacy policy — it's the architecture The usual pitch is "we take your privacy seriously." That's a promise you have to trust. I wanted it to be a fact you can verify : Open DevTools → Network, create an invoice, and count the requests. It's zero. There's nothing to upload because there's nowhere to upload it. Data lives in localStorage . The app is HTML/CSS/JS inlined into one file — no framework, no bundler, no node_modules . Download it once and it works offline forever. 2. Sharing an invoice without a database — put it in the URL hash This was the interesting constraint. How do you send someone a view-only invoice when you have no server to store it on? The trick: encode the whole document into the URL hash fragment . The fragment (everything after # ) is the one part of a URL that browsers never send to the server — it stays client-side. function shareLink ( state ) { const json = JSON . stringify ( state ); const encoded = btoa ( unescape ( encodeURIComponent ( json ))) . replace ( / \+ /g , ' - ' ). replace ( / \/ /g , ' _ ' ). replace ( /=+$/ , '' ); // base64url return location . origin + location . pathname + ' #v= ' + encoded ; } The recipient's browser reads the fragment, decodes it, and renders the invoice locally. The data rides inside the link and never touches a host — not even mine. PDF export, by the way, is just window.print() with a print stylesheet. 3. Invoices as URLs — with an npm package Because the a

Welcome to Part 2 of the JS interview series! This time we're tackling functions, scope, and the topic that trips up even experienced developers in interviews: closures . Missed Part 1? Check out Fundamentals & Data Types first. Q1. What is a closure? A closure is what happens when an inner function "remembers" and continues to have access to the variables from its enclosing (outer) function's scope, even after that outer function has already finished running and would normally have had its local variables cleaned up. This works because JavaScript functions don't just capture the values of outer variables — they capture live references to them, keeping the entire surrounding scope alive in memory for as long as the inner function itself is reachable. Closures are one of the most powerful and commonly used patterns in JavaScript. They're the mechanism behind data privacy (since variables inside a closure can't be accessed from outside except through the functions that were given access), factory functions that generate customized functions, memoization caches, and event handler callbacks that need to remember state from when they were created. In the classic counter example below, each call to counter() creates a fresh, independent count variable that only the returned function can see or modify — there's no way to reach into it from outside. function counter () { let count = 0 ; return () => ++ count ; } const inc = counter (); inc (); // 1 inc (); // 2 Q2. What is lexical scoping? Lexical scoping (also called static scoping) means that a variable's accessibility is determined entirely by where it's physically written in your source code — not by which function called which, or the order in which functions happen to execute at runtime. When JavaScript compiles your code, it can already determine, just by looking at the nesting of functions and blocks, exactly which variables any given piece of code will be able to see. This is what allows an inner function to "reach

Part 1 was about waiting well. This one is about not waiting at all, and about a couple of mistakes I...

Version 5.0.0 of eslint-rspack-plugin has been released as a pure ESM package, aligning with the Rspack ecosystem and removing its CommonJS build. The plugin continues to integrate ESLint in the build process but may affect build times. Users are advised to consider separate linting commands for efficiency. The project is open source and available via npm. By Daniel Curtis

TypeScript asserts and Type Predicates in 2026: Writing Guards That Actually Narrow Correctly This article was written with the assistance of AI, under human supervision and review. Most TypeScript runtime validation breaks down because engineers write guards that compile but don't actually narrow types where it matters. The pattern that teams overlook is the distinction between type predicates that return boolean values and assertion functions that throw on failure—and choosing the wrong one creates silent bugs that surface in production. The problem starts when developers write a function like isUser(value: unknown): boolean and expect TypeScript to understand what that boolean means. The compiler sees the function return true but has no idea that value is now safe to treat as a User type. Code that looks validated crashes at runtime because the type system never learned what the validation actually proved. The fix is adding the type predicate syntax value is User to the return signature. This tells TypeScript that when the function returns true , the narrowed type holds in the calling scope. For throwing guards that never return on failure, the asserts keyword encodes that guarantee into the signature itself. That distinction is critical. Type predicates return booleans and enable conditional narrowing. Assertion functions throw errors and narrow the remainder of the scope unconditionally. Mixing them up or using neither creates validation theater—code that runs checks but provides zero type safety. Key Takeaways Type predicates ( value is Type ) narrow types conditionally when the guard returns true , while assertion functions ( asserts value is Type ) narrow unconditionally by throwing on failure. Most guard functions fail to narrow because they return boolean instead of using predicate syntax—the compiler cannot infer type information from a plain boolean. Assertion functions are superior for null checks and invariants that should never fail, while type predic

TL;DR ABR "flapping" is when your player hops between quality levels every few seconds on a jittery network, and each hop is a visible lurch. We'll detect it from LEVEL_SWITCHED events, then fix it in layers: widen the bandwidth-estimator memory, make upswitches earn their place, and cap the switch rate with abrSwitchInterval (new in hls.js 1.7). Config + a detection snippet you can paste in today. 📦 Code: github.com/USER/hlsjs-abr-tuning, replace before publishing The bug nobody reports correctly Users don't file "my ABR is flapping." They say the video "kept changing" or "couldn't decide." What's happening: on cellular, throughput is spiky, and the player's bandwidth estimator treats every spike as the new truth. One fast segment and it jumps to 1080p, one slow segment and it drops to 240p, over and over. Low rebuffer ratio, good startup time, and still a miserable watch. Counterintuitively, feeding the player fresher bandwidth data makes this worse, because fresher data is noisier. The fix is a player with a longer memory and slower reflexes. Let's build that. 1. First, detect the flap 📊 Don't tune by vibes. Count level switches per minute of playback. Every switch fires Hls.Events.LEVEL_SWITCHED . // abr-monitor.js, hls.js 1.7.x, node 20+ tooling / any modern browser import Hls from " hls.js " ; export function attachFlapMonitor ( hls ) { const switches = []; hls . on ( Hls . Events . LEVEL_SWITCHED , ( _evt , data ) => { const now = performance . now (); switches . push ({ t : now , level : data . level }); // keep a 60s sliding window while ( switches . length && now - switches [ 0 ]. t > 60 _000 ) switches . shift (); const perMin = switches . length ; const reversals = countReversals ( switches ); if ( perMin >= 6 ) { console . warn ( `[abr] flapping: ${ perMin } switches/min, ${ reversals } reversals` ); } }); } // a "reversal" = up then down (or down then up), the signature of flapping function countReversals ( s ) { let r = 0 ; for ( let i = 2 ; i < s . l

Introduction Telegram has become one of the most popular platforms for sharing files, videos, images, and other media. However, when using Telegram Web, I found that saving media files was not always convenient. For example: downloading videos from channels saving multiple images managing large files The process usually requires several manual steps. So I decided to build a Chrome Extension to make Telegram media downloads easier. The project is called TGVideoDown. Website: https://tgvideodown.com Why build a Chrome Extension? At first, I considered building a standalone desktop application. But I realized that many Telegram users already use Telegram Web inside their browsers. A browser extension provides a simpler workflow: Open Telegram Web ↓ Find the media file ↓ Click download ↓ Save directly Users don't need: additional software complicated setup third-party upload services Technical implementation TGVideoDown is built with Chrome Extension APIs. Main technologies include: Content Script Used to interact with Telegram Web pages. Because Telegram Web is a dynamic application, the extension needs to handle: dynamic DOM updates asynchronous loading user interactions Chrome Downloads API Used to manage browser downloads. Example: chrome.downloads.download({ url: fileUrl, filename: fileName }) Storage API Used for storing user preferences and extension settings. Features Currently TGVideoDown supports: Telegram video downloads Telegram image downloads Telegram audio downloads Telegram GIF downloads Telegram file downloads Large file downloads Batch media downloading Challenges during development Handling dynamic pages Telegram Web uses a highly dynamic frontend. Traditional HTML parsing is not enough. The extension needs to monitor page changes and react when new media elements appear. Download experience Large media files require a smoother download process. The goal was to make downloading as simple as possible: Click → Download → Save Current sta

Modern backend applications handle thousands or even millions of requests every second. Users perform actions simultaneously: buying products, transferring money, updating profiles, sending messages, and more. But what happens when two requests try to modify the same data at the same time? This is where race conditions appear — one of the most subtle and dangerous problems in backend development. A race condition can cause incorrect data, security issues, financial losses, and unpredictable application behavior. Understanding how race conditions happen and how to prevent them is an essential skill for backend developers. What Is a Race Condition? A race condition occurs when multiple processes or requests access and modify shared data at the same time, and the final result depends on the order in which those operations execute. The problem is that the developer expects operations to happen in a specific sequence, but the computer executes them based on timing, network delays, database speed, and system load. Simple Example: Bank Account Withdrawal Imagine a user has: Account Balance: $100 Two withdrawal requests arrive at the same time: Request A: Withdraw $80 Request B: Withdraw $50 The backend checks the balance: Request A: Balance >= 80? Yes Request B: Balance >= 50? Yes Both requests continue because they saw the original balance of $100. The system processes: $100 - $80 = $20 $100 - $50 = $50 The final balance might become: $50 instead of: -$30 (which should have been rejected) The application has allowed money to be withdrawn that does not exist. This is a race condition. How Race Conditions Happen in Express.js Express.js applications are often built around asynchronous operations: Database queries API calls File operations Background jobs Message queues Consider this simple inventory system: app . post ( " /purchase " , async ( req , res ) => { const product = await Product . findById ( req . body . productId ); if ( product . stock > 0 ) { product . stock -

Most of us use Spring Boot every day. We create a @RestController, run the application, hit an endpoint from Postman, and get a response. But have you ever wondered what actually happens between clicking "Send" in Postman and your controller method executing? When I started digging into Spring internals, I realized there are several layers working together before my controller is even called. Here's the high-level request flow: Postman │ ▼ Operating System │ ▼ Embedded Tomcat │ ▼ Servlet Filter Chain │ ▼ Spring Security (JWT) │ ▼ DispatcherServlet │ ▼ Controller │ ▼ Service │ ▼ Repository │ ▼ Database What surprised me? One thing I misunderstood for a long time was thinking that the request directly reaches my controller. In reality: The Operating System first routes the request to the application listening on the target port (for example, 8080). Embedded Tomcat accepts the connection. The request passes through the Servlet Filter Chain. Spring Security validates the JWT (if security is enabled). Only after successful authentication does the request reach Spring MVC's DispatcherServlet, which finds the correct controller. This means your controller only executes after several infrastructure components have already processed the request. Key Takeaway Understanding this request flow makes Spring Boot feel much less "magical." Instead of memorizing annotations, you begin to understand why they work. In the next post, I'll explain how Spring Boot starts Embedded Tomcat automatically before the first request even arrives.

Node Date 的 epoch 毫秒坑 + 用 MCP 把转换塞进 AI 流 作者是 Node.js / JS 时间 方向的开发者。这篇不是广告，是踩坑记录 + 顺手做的工具。 背景 做 Node.js / JS 时间 时，时间戳转换是最常被低估的雷区。16 个时间戳工具(Unix 转换/时区/ISO8601/Cron/Duration…) 已覆盖日常；但每个语言/框架的坑都不一样，所以又补了 30 个语言/框架时间戳页(python/javascript/java/sql/…)，每页含 6 个真实坑。 我踩过的坑（举几个） 秒 vs 毫秒：前端 Date.now() 是毫秒，后端常存秒，混用差 1000 倍。 时区不是字符串：存 UTC、展示本地，别把本地时间当 UTC 落库。 2038 问题：32 位系统 time_t 在 2038-01-19 溢出，老系统要提前查。 夏令时：一年有两次重复/缺失的本地时间，跨区调度尤其坑。 我顺手做的东西 转换速查页： https://gotimestamp.com/timestamp/nodejs 相关语言页： https://gotimestamp.com/timestamp/javascript 开源 MCP： https://github.com/caresotin/tsforge-mcp —— 把时间戳转换/校验直接接进 LLM 工作流，不用手算。 小结 时间戳没那么简单，但工具到位就省心。上面都是免费、开源、可直接用的，希望对同样踩坑的人有帮助。

After working on enterprise applications and distributed microservices, I have realized that the biggest challenges rarely come from writing business logic. They come from handling production traffic, failures, concurrency, and unexpected edge cases. Here are seven lessons that every Spring Boot developer should know before calling themselves a senior engineer. 1. Never Assume an API Will Be Called Only Once One of the most common mistakes is assuming a client sends exactly one request. In reality: Users refresh the page. Mobile apps retry automatically. API gateways retry requests. Kafka consumers may reprocess events. Network failures cause duplicate submissions. If your endpoint creates an order, payment, or booking every time it receives a request, duplicates are almost guaranteed. Better Approach Design APIs to be idempotent . For example: Use an Idempotency-Key. Store processed request IDs. Ignore duplicate requests safely. Production systems should always expect duplicate requests. 2. Database Transactions Are Not Enough Many developers believe this solves everything: @Transactional public void createOrder () { ... } It doesn't. A transaction protects changes inside a single database . It does not protect: Kafka publishing Email sending External REST APIs Redis updates File uploads If your database commits successfully but Kafka publishing fails, your system is already inconsistent. Better Approach Use patterns such as: Transactional Outbox Saga Pattern Event-driven architecture Retry with dead-letter queues 3. Don't Trust External APIs Every external service will eventually fail. Your payment provider. Your authentication service. Your notification service. Even your own internal microservices. Never assume another service is always available. Add Protection Timeouts Retries Circuit Breakers Fallback logic Monitoring Failing fast is usually better than waiting forever. 4. Logging Is More Valuable Than You Think When production goes down, nobody asks: "Was th

Canonical URL: https://blog.1001020.xyz/ Suggested cover image: use a recent image from https://blog.1001020.xyz/gallery I have been building a small publishing system called 1001020 , a serverless blog and AI gallery running on Cloudflare Workers. The live site is here: 1001020 — AI Gallery & Cloudflare Experiments The goal was not to build another static blog generator. I wanted something that could publish articles, serve an image gallery, manage uploaded assets, expose structured sitemaps, and stay operational without a traditional server. The basic architecture The whole public site runs on Cloudflare Workers. Articles, settings, comments, gallery metadata, and telemetry live in Cloudflare KV. Managed images are stored in R2 and served through a dedicated image domain. The main pieces are: Cloudflare Workers for request routing and rendering Cloudflare KV for article and site metadata Cloudflare R2 for managed image uploads A theme system for different frontend layouts XML sitemap and image sitemap generation A small local AI drafting tool for preparing and publishing content The gallery is a first-class part of the site, not just a media folder. You can browse it here: AI Gallery on 1001020 Why Workers instead of a conventional backend? For this project, Workers are a good fit because the workload is mostly request routing, HTML generation, metadata reads, and small API writes. A conventional server would work, but it would add deployment and maintenance overhead that I did not need. Cloudflare Workers also make it easy to keep the app close to the edge while still handling dynamic behavior. The blog can render pages server-side, expose APIs, and support admin operations without a separate Node or container deployment. KV as the content store The project stores persistent content in KV using explicit keys for articles, gallery records, settings, telemetry, comments, newsletter subscribers, and other small datasets. This shape works well for a personal publishi

It was 2 AM, and the on-call chat was on fire again: the order service was healthy on every dashboard, but throughput had flatlined at ~800 req/s while P99 climbed past 4 seconds. The usual suspect? A thread pool sized by guesswork during a late-night deploy, six months earlier. We'd hand-tuned maxThreads to "something that felt right," and it wasn't right anymore. That's the moment I started appreciating a different default: in Solon, all of those knobs ship as 0 — meaning auto , derived from your machine's actual CPU cores at runtime. You can go months without thinking about a single thread-pool property. This post walks through the five knobs that exist, how the auto-tuning math works, and the three failure modes that tell you it's time to touch them. The five knobs under the hood Solon exposes these on app.yml (all values are the documented defaults): # Minimum threads for the http server (0 = auto; also accepts fixed values like 2, or core multiples like x2) server.http.coreThreads : 0 # Maximum threads for the http server (0 = auto; also accepts fixed values like 32, or core multiples like x32) server.http.maxThreads : 0 # Idle thread timeout in ms (0 = auto) # supported since v1.10.13 server.http.idleTimeout : 0 # Is this an IO-bound service? (default true) # supported since v1.12.2 server.http.ioBound : true # Enable the virtual thread pool (default false) # supported since v2.7.3 solon.threads.virtual.enabled : false Notice what's missing: no hard-coded defaults for coreThreads or maxThreads . 0 means "figure it out from the hardware." That single decision removes a whole class of "copy-pasted tuning values" problems — the ones that were right for someone else's 32-core box and wrong for your 2-core container. CPU-bound or IO-bound: the one question that matters The auto-tuner only needs you to answer one question: is your workload CPU-bound or IO-bound? CPU-bound : the work happens entirely in CPU and memory — think a "hello world" handler that returns a s

PR #5386 adds a pure Codename One text-editing path. EditField , RichTextArea , and CodeEditor can now keep their document, selection, and painting inside the lightweight UI while each port supplies keyboard and input-method events. What is Codename One? Codename One is an open-source framework for building native iOS, Android, desktop, and web apps from a single Java or Kotlin codebase. Learn more at codenameone.com . Text input must handle virtual keyboards, hardware keys, autocorrect, dictation, marked text from an input method editor, bidirectional text, selection, clipboard formats, and accessibility geometry. Codename One traditionally delegates that work to a native platform field placed over the lightweight component during editing. The overlay remains the default for TextField and TextArea . It can create a small visual jump, and it cannot participate in lightweight painting for syntax highlights, rich runs, masks, inline images, or a custom selection model. The port sends text operations instead of key codes A soft keyboard does not type keys. It commits words, replaces a marked composition range, deletes text around the caret, and changes selection. Dictation may insert a sentence without producing one key event. The new TextInputClient contract models those operations: commitText(...) inserts final text. setComposingText(...) replaces the active marked-text range. finishComposing() accepts that range. deleteSurroundingText(...) implements virtual-keyboard deletion. onKeyCommand(...) carries navigation, selection, clipboard, undo, and redo. Geometry queries locate the caret and selection for candidate windows and accessibility. All offsets use UTF-16 indices. That matches Java String , Android Editable , and Apple string APIs. The document normalizes line endings before it updates selection, undo history, formatting runs, or the state returned to the platform. The port still owns the keyboard session. Codename One owns the document and what appears on scr

This week's Java roundup for July 27th, 2026, features news highlighting: OpenJDK JEPs targeted and proposed to target for JDK 28; the GA release of GPULlama3.java 1.0; point releases of Micronaut, Quarkus and JobRunr; a maintenance release of JDKUpdater; the sixth release candidate of Maven 4.0; and the first milestone release of Jakarta Agentic AI 1.0. By Michael Redlich

GitHub热门项目 | Node.js based forum software built for the modern web | Stars: 15,175 | 2 stars today | 语言: JavaScript

Cómo solucionar el error “Enable JavaScript and cookies to continue” Este error aparece cuando Cloudflare (u otro proxy inverso de seguridad) detecta que el navegador del usuario no cumple con los requisitos mínimos para acceder al sitio: JavaScript está deshabilitado o las cookies no están permitidas . Pero en entornos reales, el problema suele ser más sutil: el navegador sí tiene JS y cookies habilitados, pero la configuración del entorno de ejecución (como un headless browser, test automation, o un scraper) no emula correctamente el comportamiento del cliente . 🔍 Causa raíz técnica Cloudflare emite un desafío (CAPTCHA o JS challenge) para verificar que el cliente es un navegador real. Si la respuesta no cumple con el desafío (por ejemplo, porque: El navegador no ejecuta el JS del desafío (headless sin soporte), Las cookies no se persisten entre solicitudes, El User-Agent o Accept-Language no coinciden con navegadores reales, Falta el Referer o Origin en headers, Se bloquean cookies de terceros (como las de Cloudflare), … entonces el servidor devuelve este mensaje estático en lugar de redirigir a la página solicitada. ⚠️ Nota crítica : Si estás usando herramientas como curl , requests de Python, o navegadores headless sin configuración especial, no pasarás el desafío de Cloudflare . Es intencional: Cloudflare bloquea tráfico no humano por diseño. ✅ Solución definitiva (por escenario) 🛠️ Caso 1: Navegador real (usuario final) Verifica que JavaScript esté habilitado : Chrome: Configuración → Privacidad y seguridad → Configuración de sitios → JavaScript → Permitido . Firefox: Preferencias → Privacidad y seguridad → Cookies y datos de sitios → Deshabilitar “Bloquear cookies y datos de sitios” . Limpia cookies y caché (especialmente para *.cloudflare.com ). Reinicia el navegador y vuelve a cargar la página. 🛠️ Caso 2: Automatización / Scraping (Python + Playwright/Selenium) No uses requests o urllib : no ejecutan JS. Usa un navegador real con soporte para Cloudflare. ✅

Andrea Peruffo discusses the evolution of WebAssembly beyond the browser and its growing role on the server-side JVM. He covers performance advancements in Wasm runtimes, moving from interpreters to efficient JIT compilation, and explores real-world production use cases ranging from edge computing platforms to modular plugin architectures. By Andrea Peruffo

This is a submission for DEV's Summer Bug Smash: Smash Stories powered by Sentry . Every developer has experienced that moment when a project works perfectly but doesn't feel perfect. That was exactly what happened while I was building my Gem Price Estimator , a web application designed to estimate gemstone values based on multiple characteristics and pricing rules. The calculations were accurate. The interface looked good. But something bothered me. It wasn't as responsive as I wanted it to be. That small delay was enough to make the application feel slower than it should, and I knew there had to be a better way. This wasn't about fixing a crash or a broken feature. It was about finding the hidden performance bottleneck. The Project The Gem Price Estimator analyses several gemstone properties and combines them to generate an estimated market value. The estimation process considers multiple factors, including: Carat weight Color Clarity Cut Other pricing adjustments Every user interaction triggered a complete recalculation of the estimated value. Initially, this approach worked well while the project was small. As the pricing logic became more sophisticated, however, the application started doing significantly more work than necessary. The First Sign Something Was Wrong Nothing was technically broken. There were no JavaScript errors. No failed requests. No database issues. The application simply felt slower every time users adjusted the estimator. Those tiny delays might seem insignificant individually, but together they reduced the smoothness of the overall experience. I wanted every adjustment to feel nearly instant. That became my goal. Investigating the Problem My first assumption was that the issue was caused by database operations. So I started checking: Database queries Network activity Browser Developer Tools Console logs Individual calculation steps Surprisingly... None of those were the real problem. The application wasn't waiting on the database. It wasn'