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GitHub热门项目 | Marketing skills for Claude Code and AI agents. CRO, copywriting, SEO, analytics, and growth engineering. | Stars: 31,298 | 160 stars today | 语言: JavaScript

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A walkthrough of the architecture decisions behind Flacron Gamezone a production full-stack app built with Next.js, Express, PostgreSQL, and Redis. When a client approached me to build a live football match discovery platform, the requirements sounded straightforward on the surface: show live scores, let users subscribe, handle authentication. But the moment you start thinking about how those pieces connect in production, straightforward gets complicated fast. This is the story of how I designed the backend for Flacron Gamezone — what decisions I made, why I made them, and what broke along the way. Table of Contents The Problem With "Just Building It" The Architecture: Four Distinct Layers Why This Matters to a Client The Bug That Taught Me Something Real The Full Stack at a Glance What I'd Do Differently The Problem With "Just Building It" The easiest version of this app is a single Express file: one route handler that queries the database, formats the data, and sends a response. I've seen this pattern in tutorials everywhere. It works for demos. It falls apart in production. The problems are predictable: you can't test business logic without hitting the database, a change in one feature quietly breaks another, and the moment a second developer joins the codebase, nobody knows where anything lives. I wanted to build something I could actually be proud to show an employer or a client. That meant committing to a proper layered architecture from day one, even on a project this size. The Architecture: Four Distinct Layers The entire Express backend is organized into four layers. Each layer has one job and talks only to the layer directly below it. Route → Controller → Service → Repository Here's what each one actually does. Routes are just maps. They declare that POST /api/v1/subscriptions exists, attach the auth middleware, and hand off to the controller. No logic lives here. Controllers handle the HTTP boundary. They extract data from req.body or req.params , call th

The Moment I Realized I Didn't Really Know JavaScript I was 2 months into learning JavaScript. I could use .map(), .filter(), .reduce() like any bootcamp grad. I felt confident. Then my instructor asked me one question: "How does .reverse() actually work?" I froze. I had used it hundreds of times. But I had no idea what was happening inside. I was a user, not a builder. That was the day everything changed. The 01EDU Difference: Build Tools, Not Just Use Them Most coding courses teach you to use built-in methods. 01EDU does something different. They disable the built-in methods. Then they say: "Now build it yourself." No .split(). No .join(). No .indexOf(). No .slice(). Just you, a text editor, and your brain. What I Built in 2 Weeks (Without Using Built-ins) Here are the JavaScript methods I re-created from scratch: Method What I Learned abs() Math is logic, not magic multiply(), divide(), modulo() Arithmetic is repeated addition/subtraction indexOf(), lastIndexOf(), includes() Searching is just looping and comparing slice() Negative indexes count from the end reverse() Arrays and strings are both indexed collections join() Building strings step by step split() Parsing is character-by-character inspection round(), floor(), ceil(), trunc() Decimals are just numbers between whole numbers Each function took hours of thinking, failing, debugging, and finally — understanding. The Most Painful Lesson: Loops The first time I tried to build repeat() without using .repeat(), I wrote an infinite loop. My computer froze. I had to force restart. That failure taught me more than any working code ever could. I learned to trace each iteration mentally. I learned to check my exit conditions. I learned to respect the loop. You don't truly understand loops until you've crashed your computer with one. What 01EDU Taught Me That No Bootcamp Could I learned how computers think, not just how to write code When you build .split() from scratch, you understand string parsing at a deep level.

Two file formats. Same animations. Very different performance characteristics. If you've used Lottie before, you know the .json file — you export it from After Effects with the Bodymovin plugin, drop it into lottie-web, done. But there's a newer format: .lottie. It's a binary container that replaces the JSON, and if you're starting a new project, it's worth understanding the difference. What is Lottie JSON? The original format. A .json file that describes vector animations: shapes, keyframes, layers, colors, timing. It's plain text, human-readable, and widely supported. Pros: Works everywhere Lottie is supported Human-readable (you can inspect and edit it) Supported by every tool and library Cons: Large files (uncompressed JSON with lots of repeated data) No built-in support for multiple animations in one file No metadata or preview image support What is .lottie? The .lottie format (sometimes called dotLottie) is a ZIP container with a .lottie extension. Inside it contains: The animation data (compressed JSON) A manifest.json describing the file Optional preview images Optional multiple animations in one container It was developed by LottieFiles and adopted as the preferred format for modern Lottie tooling. Pros: ~30-70% smaller than equivalent JSON (thanks to compression) Can contain multiple animations in one file Supports preview thumbnails Cleaner API in the @lottiefiles/dotlottie-web renderer Cons: Binary format — not human-readable Requires the dotLottie player (not the older lottie-web) Slightly less universal support File Size Comparison For a typical 2-second UI animation: Format Typical Size Lottie JSON (.json) 40 – 120 KB dotLottie (.lottie) 15 – 50 KB The size reduction comes from standard ZIP compression applied to the JSON content. It's meaningful on mobile connections. Converting Between Formats The easiest way to convert between .json and .lottie formats is using the free browser-based tools at IconKing . No signup required, no file size limits. Just

Every web app needs icons. How you manage them at scale — that's where most teams make mistakes. This is the complete guide to building an SVG icon system that doesn't fall apart as your app grows. Why SVG (Not Icon Fonts or PNG) Icon fonts (FontAwesome, etc.) are the legacy approach. The problems: One broken font file breaks all icons Accessibility is terrible (screen readers read the unicode character) Crispy rendering requires specific font-smoothing hacks No multi-color support PNG icons are dead for UI work. Blurry on Retina, can't be styled with CSS, fixed file per size. SVG wins: Infinitely scalable, pixel-perfect on any screen Styleable with CSS ( currentColor , fill, stroke) Accessible with proper ARIA labels Can animate with CSS or SMIL Single format handles all sizes Where to Get Free SVG Icons IconKing SVG Library — 254+ free SVG icons in flat and outline styles. Covers UI, social media, food, objects, and more. Downloadable as individual SVG, AI, or PNG files. No account required. What sets IconKing apart: many icons have matching animated Lottie versions in the Lottie library — useful when you want an animated hover state that matches your static icon. Other solid free sources: Heroicons (heroicons.com) — MIT, Tailwind-made, 292 icons Phosphor Icons (phosphoricons.com) — MIT, 1,248 icons, 6 weights Lucide (lucide.dev) — ISC, 1,400+ icons, React/Vue packages Tabler Icons (tabler.io/icons) — MIT, 5,000+ icons Method 1: Inline SVG Best for: small number of icons, need CSS styling <!-- Inline the SVG directly --> <button aria-label= "Close" > <svg width= "20" height= "20" viewBox= "0 0 24 24" fill= "none" stroke= "currentColor" stroke-width= "2" > <line x1= "18" y1= "6" x2= "6" y2= "18" /> <line x1= "6" y1= "6" x2= "18" y2= "18" /> </svg> </button> The stroke="currentColor" means the icon inherits its color from the parent element's CSS color property — trivial theming. Method 2: SVG Sprite Best for: many icons, better performance (single HTTP request) Bui

Loading states are one of the most overlooked parts of app UX. A bad spinner makes an app feel cheap. A good loading animation makes wait time feel intentional. Here's a curated list of free loading animations you can use right now, organized by format. Lottie Loading Animations (Best Quality) Lottie is the gold standard for loading animations in 2025. Files are small (5-30KB), resolution-independent, and perfectly smooth at any size. IconKing Free Lottie Loaders — 500+ free Lottie animations including dozens of loading spinners, progress indicators, and transition animations. Download as JSON, no account required. Preview any file before downloading at iconking.net/preview . Customize colors to match your brand at iconking.net/editor — swap any color in-browser. Implementation (React): import { useEffect , useRef } from ' react ' ; import lottie from ' lottie-web ' ; function Loader ({ size = 80 }) { const ref = useRef ( null ); useEffect (() => { const anim = lottie . loadAnimation ({ container : ref . current , renderer : ' svg ' , loop : true , autoplay : true , path : ' /animations/loader.json ' }); return () => anim . destroy (); }, []); return < div ref = { ref } style = { { width : size , height : size } } />; } Implementation (Vanilla JS): import lottie from ' lottie-web ' ; lottie . loadAnimation ({ container : document . getElementById ( ' loader ' ), renderer : ' svg ' , loop : true , autoplay : true , path : ' /animations/loader.json ' }); Convert Lottie Loaders to GIF Need the loading animation as a GIF for emails, Notion docs, or environments where you can't run JavaScript? Free Lottie to GIF Converter — upload your JSON, get a GIF. Browser-based, no signup. Other export formats available at iconking.net: Lottie to WebP — animated WebP, smaller than GIF Lottie to APNG — animated PNG with transparency Lottie to MP4 — for video embeds Lottie to WebM — transparent video Lottie to SVG — static frame as SVG CSS SVG Spinners (Zero Dependencies) For simple l

Lottie animations are small, crisp, and interactive. This guide covers finding free animations through production-ready implementation. What Is Lottie? Lottie is a JSON-based animation format from Airbnb. After Effects animations are exported via Bodymovin as small JSON files (10-100KB), rendered by a lightweight JS library. Key advantages over GIF: 10-50x smaller file size Resolution independent vector quality on any screen Interactive — play, pause, seek, speed control Full alpha transparency — no halo effects Step 1: Get Free Lottie JSON Files IconKing Free Lottie Library — 500+ free animations: UI icons, loaders, flags, illustrations. No account needed. Preview any file first: iconking.net/preview — drag and drop to instantly see how it plays. Edit colors and speed: iconking.net/editor — swap colors, adjust timing, all in-browser. Step 2: Install lottie-web npm install lottie-web Or CDN: <script src= "https://cdnjs.cloudflare.com/ajax/libs/bodymovin/5.12.2/lottie.min.js" ></script> Step 3: Basic Implementation import lottie from ' lottie-web ' ; const animation = lottie . loadAnimation ({ container : document . getElementById ( ' lottie-container ' ), renderer : ' svg ' , loop : true , autoplay : true , path : ' /animations/my-animation.json ' }); Step 4: React Component import { useEffect , useRef } from ' react ' ; import lottie from ' lottie-web ' ; function LottieAnimation ({ src , loop = true , size = 200 }) { const ref = useRef ( null ); useEffect (() => { const anim = lottie . loadAnimation ({ container : ref . current , renderer : ' svg ' , loop , autoplay : true , path : src }); return () => anim . destroy (); }, [ src ]); return < div ref = { ref } style = { { width : size , height : size } } />; } Step 5: Playback Controls animation . play (); animation . pause (); animation . setSpeed ( 1.5 ); animation . goToAndStop ( 30 , true ); // frame 30 animation . playSegments ([ 0 , 60 ], true ); // frames 0-60 only animation . addEventListener ( ' complete

You hit "Submit Order" and nothing happens. The spinner just spins. Is it processing? Did the request get lost? You click again. If the API on the other end does not implement idempotency, you just placed two orders. Maybe two charges to your card. This is a solved problem — and the solution is simpler than you think. What Is Idempotency? An operation is idempotent if doing it multiple times produces the same result as doing it once. GET requests are naturally idempotent — fetching a resource does not change it. DELETE is also idempotent in practice. The trouble is POST and PATCH : create an order twice, and you get two orders. An idempotency key is a client-generated unique identifier (usually a UUID) that you send with a mutating request. The server stores this key with the result. If the same key arrives again — whether due to a retry, a network blip, or an impatient user — the server returns the cached result instead of executing the operation again. Implementing Idempotency on the Server Here is a minimal Express implementation backed by Redis: const express = require ( " express " ); const redis = require ( " ioredis " ); const { v4 : uuidv4 } = require ( " uuid " ); const app = express (); const cache = new redis (); app . use ( express . json ()); // TTL for idempotency records: 24 hours const IDEMPOTENCY_TTL = 86400 ; async function idempotencyMiddleware ( req , res , next ) { const key = req . headers [ " idempotency-key " ]; if ( ! key ) return next (); // optional on GET/DELETE const cached = await cache . get ( `idem: ${ key } ` ); if ( cached ) { const { status , body } = JSON . parse ( cached ); return res . status ( status ). json ( body ); } // Intercept the response to cache it const originalJson = res . json . bind ( res ); res . json = async ( body ) => { if ( res . statusCode < 500 ) { await cache . setex ( `idem: ${ key } ` , IDEMPOTENCY_TTL , JSON . stringify ({ status : res . statusCode , body }) ); } return originalJson ( body ); }; next ();

There's a question that keeps surfacing across engineering teams — sometimes in architecture reviews,...

We have watched tokens stream in from an LLM before where they appeared one at a time, like the model was typing. If you used the Anthropic SDK's .stream() method, it just worked and you probably never saw what was on the wire. This post will majorly focus on how a stream response works and how bugs are handled by SDK behind the hood. 1. Why Streaming exists To enable the streaming option we would need to make one change in the post request that is a single field "stream": true and it will change the response experience. Here are the pointers we take from the gif. The left side shows no streaming as the cursor blinks for 4 seconds then the whole response lands at once. The right side shows the streaming where the first word shows up in about 300 milliseconds. Words flow in as the model generates them. Both the sides have same model, same prompt, same total time it is just the right side started giving response almost 4 seconds earlier. The 4 seconds wait time for a full reply feels broken. A streamed reply that finishes in four seconds feels fast. Streaming doesn't make the model faster it makes the wait disappear. 2. What's on the wire When you set stream: true , the API stops sending a single JSON blob. It opens a persistent HTTP connection and pushes events down the line as the model generates them. The format is Server-Sent Events (SSE) a web standard. Any SSE debugger will read this stream. Here's what comes through: A few things to notice: The text lives in delta.text , nested inside content_block_delta events. Those are the events we should look after. stop_reason moved. In post 1 , we saw it right there in the response JSON. Here, it arrives at the very end inside a message_delta event, just before message_stop . If the loop bails out as soon as the text stops arriving we will never see it. Chunks don't line up with tokens or words. You might get "Hello" in one chunk and " world" in the next, or both in one. The network decides where the cuts happens and it

A circular dependency is one of the few bugs that passes every check your toolchain runs. TypeScript compiles it cleanly. The tests pass. The build succeeds. The app ships. And somewhere deep in your import graph, a developer is staring at a TypeError: X is not a constructor that disappears the moment they add a console.log . Here are the three patterns that create them, what Node.js, webpack, Rollup, and esbuild actually do with them — they don't solve the problem, they each make a different tradeoff — and how to stop them from forming. What a circular dependency actually is A circular dependency exists when module A imports from module B, which imports — directly or transitively — from module A. // user.service.ts import { formatUser } from ' ./user.utils ' ; // user.utils.ts import { UserService } from ' ./user.service ' ; // ← closes the loop Neither developer planned this. user.service.ts needed a formatter. user.utils.ts needed the service type for a helper added three sprints later. Nobody saw the cycle form — they just saw two reasonable imports. This is how every circular dependency is born: through incremental, individually sensible decisions. The 3 patterns that create them 1. Barrel files ( index.ts re-exports) Barrel files are the biggest source of accidental cycles in TypeScript projects. // features/user/index.ts — re-exports everything in the feature export { UserService } from ' ./user.service ' ; export { UserRepository } from ' ./user.repository ' ; export { UserController } from ' ./user.controller ' ; export { formatUser , validateUser } from ' ./user.utils ' ; Now every file in the user feature imports from ../user (the barrel) for cleaner paths. And any utility the barrel re-exports cannot safely import anything else from the barrel without creating a cycle. // user.utils.ts import { UserService } from ' ../user ' ; // ← imports the barrel // The barrel re-exports user.utils → user.utils imports the barrel → cycle Teams adopt barrel files for

1. Stale closure & primitive capture What is the output of the following code? function createIncrement () { let count = 0 ; const message = `Count is ${ count } ` ; function increment () { count ++ ; } function log () { console . log ( message ); } return { increment , log }; } const { increment , log } = createIncrement (); increment (); increment (); log (); Test your understanding of closures, lexical scope, and primitive value capture. ✅ Output Count is 0 🧠 Explanation This is a classic stale closure trap — but not in the way most developers expect. Step-by-step execution: createIncrement() is invoked → new lexical environment created: count = 0 (mutable binding) message = "Count is 0" (primitive string, interpolated immediately at assignment) Inner functions increment and log are defined. Both close over the same lexical environment. increment() is called twice: count mutates: 0 → 1 → 2 ✓ This works as expected. log() is called: It references the variable message message still holds the original string value "Count is 0" The template literal was evaluated once, at the moment of assignment — not re-evaluated when log() runs. 🔑 Core Concept > Closures capture variables , not expressions . > But if a variable holds a primitive value (string, number, boolean), that value is fixed at assignment time. message is not a live reference to count . It is a snapshot . 🛠 How to fix it (if dynamic output is desired) Re-evaluate the template literal inside log() : function log () { console . log ( `Count is ${ count } ` ); } 🎯 What this question tests Concept Why it matters Template literal evaluation timing They run at assignment, not at access Primitive vs reference types Primitives are copied by value; objects/arrays are referenced Closure capture semantics Closures close over bindings, but the value of a primitive is immutable once assigned Mental model of "live" variables Not all variables in a closure are "live views" — only the bindings themselves are 2. JavaScript co

In this post i'm gone explain liked list an famous leetcode problem that is " Remove Nodes from linked list ". Problem Statement: You are given the head of a linked list. Remove every node which has a node with a greater value anywhere to the right side of it. Return the head of the modified linked list. Example 1: Input: head = [5,2,13,3,8] Output: [13,8] Explanation: The nodes that should be removed are 5, 2 and 3. Node 13 is to the right of node 5. Node 13 is to the right of node 2. Node 8 is to the right of node 3. Explanation: In this problem statement state that remove the nodes which have the right side (any place) element greater than. let's understand with given example. Node 13 is the right side of the 5,2 nodes thats why 2,5 should be remove. Node 8 is the right side of 3 node thats why 3 should be remove. final result would be [13,8] Solution of the problem: `/** * Definition for singly-linked list. * function ListNode(val, next) { * this.val = (val===undefined ? 0 : val) * this.next = (next===undefined ? null : next) * } */ /** * @param {ListNode} head * @return {ListNode} */ const reverList = function(head){ let prev = null; let curr = head; let next = null; while(curr!=null){ next = curr.next; curr.next = prev; prev = curr; curr = next; } return prev; } var removeNodes = function(head) { // reverse list let reversList = reverList(head); let maxNode = reversList; let prevNode = reversList; let currNode = reversList.next; // removed list while(currNode != null){ if(maxNode.val > currNode.val){ currNode = currNode.next; }else{ maxNode = currNode; prevNode.next = currNode; prevNode = prevNode.next; currNode = currNode.next; } } prevNode.next = null; // reverse list return reverList(reversList); };` If you have any query or suggestions leave your expression👨🏿‍💻🙌.

GitHub热门项目 | 使用 NextJS + Notion API 实现的，支持多种部署方案的静态博客，无需服务器、零门槛搭建网站，为Notion和所有创作者设计。 (A static blog built with NextJS and Notion API, supporting multiple deployment options. No server required, zero threshold to set up a website. Designed for Notion and all creators.) | Stars: 11,496 | 44 stars this week | 语言: JavaScript

GitHub热门项目 | The React Framework | Stars: 139,608 | 19 stars today | 语言: JavaScript

GitHub热门项目 | CodeVibe is an interactive learning platform designed to help beginners understand programming through simple lessons and hands-on practice. It includes structured course sections, coding examples, and a built-in HTML compiler that lets users write and test code directly in the browser, making learning web development practical, engaging. | Stars: 28 | 2 stars today | 语言: JavaScript

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GitHub热门项目 | Open-source alternative to AI video platforms — Free AI image & video generation studio with 200+ models (Flux, Midjourney, Kling, Sora, Veo). No content filters. Self-hosted, MIT licensed. | Stars: 17,522 | 138 stars today | 语言: JavaScript