JavaScript

A practical, senior-dev guide to property descriptors, getters/setters, defaults that surprise people, and real-world recipes you’ll actually reuse. Introduction Most of us create properties like this: obj.count = 1; It “just works”… until you need read-only fields, non-enumerable metadata, lazy getters, validation on assignment, or deprecation shims. That’s when Object.defineProperty becomes the right tool. The flip…

From circular references to BigInt, Dates, and custom replacers — how to serialize JavaScript objects safely and predictably. Introduction At first glance, JSON.stringify looks simple: JSON.stringify({ a: 1 });// ‘{“a”:1}’ But real-world objects are messy: nested structures, Dates, Maps, Sets, circular references, undefined, NaN, BigInt, and sensitive fields you want stripped. If you just call JSON.stringify blindly,…

How to throttle noisy state changes, avoid localStorage jank, and keep your UI snappy with debounce patterns for object updates. Introduction Imagine you’re storing form data or app state in the browser: window.addEventListener(“input”, e => { state[e.target.name] = e.target.value; localStorage.setItem(“formState”, JSON.stringify(state));}); Problem: every keystroke triggers a localStorage write. That means blocking synchronous calls on the main…

Practical recipes for blazing-fast lookups in the browser and Node — keys, eviction (TTL/LRU), invalidation, memory safety, and TypeScript-friendly utilities. Introduction You fetch a user by ID five times in one minute. The data barely changes, yet your app keeps hitting the network and re-rendering. That’s wasted time and money. The good news? A tiny, boring tool…

Understanding the Event Loop, Web APIs, and Concurrency without losing your sanity Introduction You’ve probably heard this before: “JavaScript is single-threaded.” That’s true… but also not the full picture. Yes, JavaScript runs one piece of code at a time in a single call stack. But modern JS can handle timers, I/O, DOM events, async/await, and even…

Demystifying one of JavaScript’s most misunderstood concepts — with clear rules, examples, and gotchas. Introduction If you’ve ever seen an error like: ReferenceError: Cannot access ‘x’ before initialization …you’ve encountered the Temporal Dead Zone (TDZ). Despite being around since ES6 (2015), the TDZ still confuses beginners (and even some intermediate developers) in 2025. Why? Because it feels inconsistent…

Build a tiny, fast, chainable utility library from scratch — complete with lazy evaluation, mixins, and TypeScript types. Introduction Fluent, chainable APIs are addictive: _(users).map(‘name’).filter(Boolean).sortBy().take(5).value(); They read like English, encourage small reusable steps, and keep state local to the chain. Lodash popularized the style with _.chain() and later implicit chaining via _(). But you don’t need a…

Speeding up expensive function calls with caching strategies you can write by hand Introduction Every developer has faced this: a function runs fine the first time, but when called repeatedly — especially with the same inputs — it becomes a performance bottleneck. That’s where memoization comes in. Memoization is a fancy word for a simple idea: cache the results of…

Why Immediately Invoked Function Expressions still matter in modern JavaScript. Introduction Before ES6 modules, IIFEs (Immediately Invoked Function Expressions) were everywhere. They powered jQuery plugins, AngularJS, and even big frameworks like React in its early days. Today, with import/export and let/const, many devs think IIFEs are dead. But here’s the truth: IIFEs are still a…