Functional Programming

Stop unnecessary network calls, prevent race conditions, and make your app snappier with these practical examples. Introduction Here’s a dirty secret: Even experienced developers let old Fetch requests keep running in the background, wasting time, bandwidth, and sometimes even breaking the UI. That’s why the AbortController API exists to give you full control over in-flight requests.…

Learn how to cancel fetch requests, prevent race conditions, and save bandwidth the modern way. Introduction Let’s start with a pain every dev knows 👇 You type in a search bar that fetches results on each keystroke.You type “React”, and it sends 5 requests:R → Re → Rea → Reac → React By the time the…

Both send HTTP requests, but only one feels modern. Here’s how Fetch simplifies everything XHR made complicated. Introduction Before fetch() arrived, XMLHttpRequest (XHR) was our only way to make HTTP calls in JavaScript. It worked… but it was messy: Then came Fetch, and everything changed. The Fetch API isn’t just a newer way to do…

The Fetch API looks simple, but it hides gotchas that break real-world apps. Here’s how to avoid the mistakes most developers still make. Introduction If you’ve ever written: fetch(“/api/data”).then((res) => res.json()).then(console.log); …it works fine until it doesn’t. Maybe your response isn’t JSON.Maybe the request never ends.Maybe the server returns 500, but your app says everything’s fine.…

It’s 2025, yet most codebases still misuse Fetch by omitting error checks and implementing broken retries. Here’s how to actually do it right. Introduction You’ve seen this line a thousand times: fetch(“/api/data”).then((res) => res.json()).then(console.log); Looks fine, right?Except it silently fails on 404s, swallows timeouts, and floods logs when the network hiccups. The Fetch API is powerful…

Everything you need to know, from simple GET requests to advanced error handling, retries, and streaming responses. Introduction For years, we used it XMLHttpRequest like it was black magic.Then came fetch(), a modern, promise-based, and far cleaner approach. But here’s the catch: Even experienced developers misunderstand how Fetch actually handles errors, timeouts, and responses. This…

Understand what’s really happening behind Express, Redux, and Koa by building your own middleware system from scratch. Introduction If you’ve ever written something like this in Express: app.use((req, res, next) => { console.log(“Request received!”); next();}); …you’ve already used middleware, but do you know how it actually works? Most developers think middleware is a framework feature. In reality,…

Stop wiring callbacks manually, learn how pub–sub makes your code modular, scalable, and surprisingly elegant. Introduction Let’s be honest, JavaScript apps are full of “when this happens, do that” logic. It’s easy to start with callbacks or addEventListener()but as your app grows, everything ends up tangled together. That’s where the Publish–Subscribe pattern (or Pub–Sub) shines.…

Learn how to limit function calls in high-frequency events like scroll and resize, no Lodash, no magic. Introduction You’ve probably seen this before: window.addEventListener(“scroll”, () => { console.log(“scrolling…”);}); Now open the console and scroll a little. 🔥 Boom, hundreds of logs per second. That’s because the scroll event fires continuously. If you run heavy code (like recalculating…

Both limit how often functions run, but they behave very differently. Let’s finally end the confusion with simple visuals and real examples. Introduction If you’ve ever said “throttle” when you meant “debounce”, you’re not alone. Developers mix them up all the time because both: But they’re not the same thing; in fact, they solve opposite…