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How race time predictors actually work: Daniels VDOT vs Riegel, with the JavaScript
Every race time predictor on the internet is doing one of two things. It is either fitting a power law to your result (Pete Riegel, 1981) or running you through a physiology model (Jack Daniels and Jimmy Gilbert, 1979). I implemented both in plain JavaScript for a running app I work on, so here is how they actually work, with the code. Method 1: Riegel's power lawRiegel was a mechanical engineer and a competitive runner. In 1981 he fit a simple relationship to world-record performances: fin
Building a Personal Knowledge Graph for Developers to Accelerate Problem Solving
Building a Personal Knowledge Graph for Developers to Accelerate Problem Solving Building a Personal Knowledge Graph for Developers to Accelerate Problem SolvingA well-structured personal knowledge graph (PKG) helps developers capture ideas, decisions, and learnings so you can reason faster and reuse insights across projects. This tutorial guides you through designing, implementing, and using a PKG tailored for software engineers. Youβll end with a ready-to-run example you can adapt t
Building a Shared Workspace State Layer for AI Coding Tools
The AI coding ecosystem is fragmenting.Some developers prefer Cursor.Others use Claude Code.Many are experimenting with Gemini CLI, Codex, and MCP-powered workflows.The challenge isnβt choosing the best model.The challenge is maintaining a consistent understanding of the project while moving between tools.The Context ProblemMost AI assistants rely heavily on:Chat historyContext windowsPrompt engineeringThese approaches work well inside a single session.They break down when developers switch tool
How to Convert Supplier CSVs to Shopify/Amazon/WooCommerce Without Uploading to a Server
Every e-commerce supplier sends files differently. One uses REF and DESIGNATION, another uses SKU and Description. Some ship XLSX with merged cells. Others hand you a UTF-16 CSV that Excel refuses to open.The traditional solution: upload to a server, wait for parsing, hit errors, fix the file, repeat. This wastes time and exposes sensitive pricing data to a third party.I built SKUMart β a client-side CSV/XLSX converter that auto-detects columns in 6 languages and maps them to Shopify, Amazon, Wo
Content Writing Service
Content Writing Servicehttps://www.realmacways.com/content-writing-service/Our agency company understands the power of words and their ability to captivate and inspire. With Real Macways, you can have engaging and custom content writing service help that speaks directly to your audience and reflects your brand online unique voice.Website contentBlog and articleSocial media contentEmail marketingCustom content for BrandsE-commerce product descriptionsDevelopment ImageDevelopment ImageUnderstandin
Why I built OrganizeShots β a browser-based screenshot organizer
I had 500+ screenshots on my phone β OTPs, payments, WhatsApp chats β all mixed up. Finding anything was impossible.Existing apps required cloud upload β which is a privacy risk. Your OTPs and payment receipts should never leave your device.So I built OrganizeShots:Drag & drop your screenshotsAuto-sorts into smart folders β OTP, Payments, WhatsApp, Social MediaDownload ZIPEverything in your browserNothing uploaded100% private and freeTry it: https://www.organizeshots.comWould love your feedb
CSS text-transform vs a Real Case Converter: What's the Difference?
CSS has a text-transform property. So why do developers reach for a case converter tool? Because CSS text-transform only handles visual display β it doesn't change the underlying text. Here's when each approach is right. CSS text-transformtext-transform is a presentational property that changes how text renders in the browser without altering the actual value in the DOM..uppercase { text-transform: uppercase; }.lowercase { text-transform: lowercase; }.capitalize { text-transform: capitalize
UUID v4 vs UUID v7 vs ULID vs NanoID: Which Should You Use?
When you need a unique identifier in your app, you have options. UUID v4 is the classic choice, but UUID v7, ULID, and NanoID each solve specific problems better. Here's when to use each. UUID v4 β The Classic (Random)UUID v4 is 128 bits of cryptographically random data, represented as:550e8400-e29b-41d4-a716-446655440000Format: 36 characters (32 hex digits + 4 dashes)Pros:Universal support β every database, ORM, and language has a UUID v4 libraryCryptographically unpredictable β safe to ex
Introduction to JavaScript
Introduction to JavaScriptJavaScript is a versatile, dynamically typed programming language that brings life to web pages by making them interactive. It is used for building interactive web applications and supports both client-side and server-side development.Interpreted language: Code is executed line by line.Dynamically typed: Variable types are determined at runtime.Single-threaded: Executes one task at a time (but supports asynchronous operations).Features of JavaScriptHere are some key fea
Mastering JavaScript Fundamentals
JavascriptJavaScript is a high-level, interpreted programming language that makes websites interactive and dynamic. It is a versatile, dynamically typed programming language that brings life to web pages by making them interactive. It is used for building interactive web applications and supports both client-side and server-side development.Interpreted language: Code is executed line by line.Dynamically typed: Variable types are determined at runtime.Dynamic means Systems or pages that adjust, r
5 Common JSON Errors and How to Fix Them Fast
JSON is everywhere β API responses, config files, data pipelines. And JSON errors have a habit of appearing at the worst moments. Here are the five most common JSON syntax errors, why they happen, and how to fix them. 1. Trailing CommaError: Unexpected token } or Unexpected token ]// β Invalid{ "name": "Alice", "age": 30,}// β
Valid{ "name": "Alice", "age": 30}Why it happens: JavaScript object literals allow trailing commas, so developers copy-paste JS code into JSON. JSON (defined by R
How I Built a Multi-Tenant SaaS ERP Using React, FastAPI and MongoDB β As a Commercial Rep With No CS Degree
I wasn't always just a sales rep.At 14, I was teaching myself HTML from internet forums β building pages just to see if I could. At 17, I was deep in IRC communities, fascinated by how systems worked under the hood. Pure curiosity. I wanted to understand the mechanics of everything digital around me.For years I automated everything I could in Excel with macros and VBA. If there was a repetitive task, I built something to eliminate it. That instinct never left.But life took me in a different dire
#javascript #apnacollege #webdev #beginners
Hello Dev Community! πIt is Day 9 of my journey toward the MERN stack! Today, I followed Lecture 2 of Apna College's JavaScript course, which transitions from storing data to actually manipulating it and making decisions.Yesterday was about variables; today was about giving the code a "brain" to choose different paths based on conditions. π§ Key Learnings From JS Lecture 2Here is the exact breakdown of the concepts I cracked today: 1. JavaScript OperatorsBefore making decisions, code ne
Tired of SEO Spam? Building a Static-First Directory for 85+ AI Tools
We have all been there. You need a simple background remover or want to compare DALL-E 3 pricing against Midjourney, but search results are clogged with heavily optimized SEO spam, aggressive paywalls, and outdated blog posts.I got tired of clicking through dozens of spammy sites just to find a simple, functional free stock photo resource or a reliable AI image upscaler. So, I did what any developer does: I spent a weekend building my own curated database hub, ImageNav, to solve this tool-fatigu
Building an Accessible Autocomplete in React
Building an Accessible Autocomplete in React Building an Accessible Autocomplete in ReactAn accessible autocomplete is a great frontend project because it combines real UI state, keyboard interaction, async data fetching, and careful focus management. This guide walks through a production-style implementation with reusable code patterns, including debounced search, keyboard navigation, and screen-reader-friendly announcements. What weβre buildingWeβll build a search box that sugg
two strangers. one call. no names
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Cessation of public development of Kefir C compiler
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How I built a free financial calculator suite for India in vanilla JS (no frameworks)
I got frustrated with existing Indian finance calculators. They're slow, cluttered, require logins, and most don't understand Indian-specific products like step-up SIPs, floating rate EMI tracking, or the old vs new tax regime.So I spent a few weeks building one from scratch. What it doesHome Loan EMI with full month-by-month amortisation tablePrepayment tracking β add a lump sum on any month and see exact interest savedSIP, Step-up SIP and Lumpsum projectionsFD & RD maturity calculator
React 19.2: Activity, useEffectEvent & React Compiler β A Practical Deep Dive (2026)
React 19.2 is the most practically significant React release since 19.0. Three major features shipped simultaneously β and together they change how you should structure React apps in 2026.Most articles describe what these features are. This guide goes further: real before/after code, when not to use each feature, and a safe upgrade path.π Full deep dive with all code examples: React 19.2 Complete Guide β WebToolsHub What Shipped in React 19.2<Activity /> β hide UI without losing state
Building a Search-as-You-Type Combobox in React
Building a Search-as-You-Type Combobox in React Building a Search-as-You-Type Combobox in ReactA search-as-you-type combobox is a great frontend pattern because it combines fast filtering, cancellation-safe data fetching, and keyboard accessibility in one UI. This guide walks through a production-friendly implementation with debouncing, AbortController, ARIA combobox semantics, and optimistic selection handling. Why this pattern mattersTypeahead inputs are deceptively hard becaus
