Intl.NumberFormat and Intl.RelativeTimeFormat: The Traps

Intl.NumberFormat and Intl.RelativeTimeFormat replace your formatting library. Defaults, traps, and the 58x performance mistake to avoid.

The flat() and flatMap() methods

Learn how JavaScript's flat() and flatMap() work: default depth, flat(Infinity), dropping holes, and using flatMap as a combined map and filter.

JavaScript Generators: Writing Iterators With yield

JavaScript generators explained: write lazy iterators with yield, handle infinite sequences, and skip the protocol boilerplate.

JavaScript Set Methods: Native Set Theory, Finally

Seven new methods landed on JavaScript's Set: union, intersection, difference, and more. Baseline since 2024. A practical guide with real-world examples.

Promise.withResolvers(): The Deferred Pattern Built-In

Promise.withResolvers() replaces the manual deferred pattern in JavaScript. One destructuring, no executor, no let. ES2024, supported in all modern runtimes.

`using` in JavaScript: Automatic Resource Management

Learn how the new using keyword and Symbol.dispose replace try/finally for cleaner resource management in JavaScript. With ES2026 support details.

Closures Explained: How Functions Remember Their Scope

A function in JavaScript remembers the scope it was created in, even after that scope has finished executing. Learn what closures are, why the loop bug happens, and how to use them in practice.

JavaScript finally gets dates right

JavaScript's Date object is 30 years old, copied from Java, and never really fixed. Temporal is the native API that finally gets dates right: immutable, timezone-aware, and no more dividing by 86400000.

Nullish Coalescing Operator

Understand the difference between || and ?? in JavaScript, and learn how the nullish coalescing operator avoids common pitfalls with falsy values like 0, empty strings, and false.