JavaScript
23 min
JavaScript Web Workers: Keep the UI Smooth While Running Heavy Code
Web Worker tutorials always need a separate worker.js file and a build tool. This one doesn't. Learn inline workers with Blob URLs (no separate file), a worker pool you build from scratch, transferable objects benchmark showing 100-300× speed difference, Comlink for ergonomic worker APIs, OffscreenCanvas for jank-free animations, SharedArrayBuffer + Atomics with the COOP/COEP headers you need, the structured clone gotchas, modern Vite/React syntax, and the exact threshold when workers hurt instead of help.
JavaScript
23 min
JavaScript Memory Leak Fix: 6 Patterns + DevTools Walkthrough
Every memory leak tutorial tells you to open DevTools without giving you actual leaks to practice on. This guide has 6 live triggerable leaks built into the demo — open DevTools alongside and watch memory grow in real time. Covers the three-snapshot technique, queryObjects() DevTools trick, observer-disconnect (ResizeObserver / IntersectionObserver), AbortController unified cleanup, performance.measureUserAgentSpecificMemory() for production, React useEffect cleanup, WeakMap/WeakRef + FinalizationRegistry caveats, and real KB-per-minute growth numbers.
JavaScript
23 min
JavaScript Debounce vs Throttle: Real Difference With Live Numbers
Every debounce vs throttle article says 'throttle fires 30-50 times, debounce fires once' — but nobody shows it happening live. This tutorial has a firing-timeline visualiser that tracks every call with real millisecond timestamps, plus the leading edge pattern nobody explains, the rAF throttle nobody covers, the AbortController + debounce fetch pattern, React 18 useDeferredValue comparison, TypeScript signatures, and the wrong-tool bugs nobody demonstrates.
JavaScript
23 min
JavaScript Event Loop Explained — Visual Interactive Demo
The JavaScript event loop is the engine behind every setTimeout, Promise, and async/await call you write. This guide is an interactive event loop visualizer — five step-by-step scenarios where you watch the call stack, microtask queue, and macrotask queue update in real time. Covers browser AND Node.js event loop phases, process.nextTick vs setImmediate, the scheduler.yield() API for INP optimization, and the MessageChannel trick React uses.
JavaScript
25 min
JavaScript async/await Not Working? 12 Mistakes That Break Your Code
async/await looks simple until it silently breaks — your function returns Promise {pending}, your forEach loop finishes before the data arrives, a 404 sails past your catch block, a search response from 2 seconds ago overwrites the one you wanted, or an error disappears with no trace. This guide shows 12 mistakes with the exact broken output, why it happens, and the precise fix.
JavaScript
25 min
Build a JavaScript AI Agent From Scratch (No Framework)
Every AI agent tutorial uses Python, LangChain, or Mastra. This one doesn't. Build a complete ReAct agent from scratch in vanilla JavaScript — the actual while loop, Thought/Action/Observation cycle, memory, guardrails, parallel tool calls, hallucinated-tool-name protection, and a 20-line DIY observability trace, all in a streaming browser UI that shows the agent thinking in real time.
JavaScript
26 min
AI That Reads PDFs in JavaScript — Three Strategies
Every AI PDF tutorial uses Python and LangChain. This one doesn't. Learn three pure JavaScript strategies for making AI read PDFs — direct text extraction, GPT-4o Vision for scanned documents, and structured JSON extraction — all in a single browser file. Plus the PDF.js worker gotchas, the API-key-in-the-browser elephant, and a free Tesseract.js OCR fallback nobody documents.
JavaScript
25 min
Vercel AI SDK in Plain JavaScript (No Next.js)
Every Vercel AI SDK tutorial assumes Next.js. This one doesn't. Learn how to use AI SDK Core in a plain Node.js script, build a minimal Express server that streams to vanilla HTML, switch providers with one line, and generate structured JSON with Zod — zero framework required.
JavaScript
15 min
WebLLM: Run LLMs in the Browser with JavaScript
WebLLM uses WebGPU to run quantized Llama, Phi, Gemma, and Mistral models entirely inside your browser tab. No server, no API key, no data ever sent to the cloud. The model downloads once, caches in the browser, and runs at near-native GPU speed.
JavaScript
13 min
Build a RAG App in the Browser with JavaScript
RAG lets AI answer questions about your own documents by retrieving the most relevant passages before generating a response. This tutorial builds a complete in-browser RAG system in vanilla JavaScript — embeddings, vector search, and GPT generation all without a backend.
JavaScript
14 min
OpenAI Function Calling in JavaScript (Vanilla JS Guide)
Function calling lets the AI decide when to invoke your own JavaScript functions and what arguments to pass. The result: AI that fetches real data, runs calculations, searches your database, and controls your UI — all driven by natural language.
JavaScript
14 min
Run AI Locally with Ollama and JavaScript
Ollama lets you run powerful AI models like Llama 3, Mistral, and Gemma entirely on your own machine — free forever, no API key, zero data sent to the cloud. This tutorial shows you how to call Ollama from JavaScript with the same fetch pattern you already know.