Patterns

Encapsulate state, expose a clean public API, avoid global leaks, and make legacy or script-tag projects maintainable without a build step. Introduction: Why this pattern still matters In a world of ES modules and bundlers, you might think the Revealing Module Pattern (RMP) is obsolete. It isn’t. Any time you: …the RMP gives you encapsulation via closures…

Control, validate, or extend access to objects in powerful ways without touching their original code. Introduction: Why Proxy? Have you ever wanted to: That’s exactly what the Proxy Pattern is for. In classic design patterns, a Proxy acts as a stand-in (or “middleman”) between the client and the real object. In JavaScript, ES6 made this trivial with…

Add logging, retries, caching, access control, and rate limits to your code without changing the original implementation; wrap it. Introduction: What “Decorator” really means (in JS that ships today) In the GoF sense, a Decorator is a wrapper that preserves an object’s interface while adding behavior before/after delegating to the original. In JavaScript, you don’t need language-level…

Create objects without new-noise, kill switch jungles, and make your codebase easier to test and extend with modern JavaScript (and a pinch of TypeScript). Introduction: Why factories matter in 2025 You’ve probably seen this shape somewhere in your code: switch (kind) { case “stripe”: return new StripeClient(cfg); case “paypal”: return new PaypalClient(cfg); default: throw new Error(“Unknown…

Singletons ensure “only one instance” of something. Here are 5 real-world cases in JavaScript where that’s exactly what you need. Introduction: Why Do We Need Singletons? Sometimes, you don’t want multiple copies of the same thing floating around in your app. That’s where the Singleton Pattern comes in:👉 It ensures only one instance of a class/object…

Learn how to build your own publish/subscribe system in plain JavaScript, no frameworks required. Introduction: Why Care About the Observer Pattern? You already use the Observer Pattern every day, even if you don’t know it: The pattern boils down to one idea: 👉 One subject notifies many observers whenever it changes. Think of YouTube subscriptions: the channel…