Why arrays with “holes” behave weirdly, how they differ from undefined, and what every developer should know before they bite…

structuredClone, libraries, and DIY recipes—plus the pitfalls with Dates, Maps, Sets, typed arrays, class instances, circular refs, and performance. Introduction…

How to use computed property names, symbols, and expressions as object keys — safely and effectively in real-world code. Introduction Have you…

Turn objects into arrays of key–value pairs and unlock powerful patterns for iteration, transformation, and real-world dev workflows. Introduction Ever…

How to turn key–value pairs into objects, invert maps, filter entries, and unlock elegant patterns in modern JavaScript. Introduction You’ve…

A practical, senior-dev guide to ?., ?.(), and ?.[]—how to write safer JavaScript/TypeScript without the pyramid of &&, plus real-world patterns, React usage,…

Stop breaking on 0, ”, or false—why ?? is better than || for safe, predictable defaults in JavaScript and TypeScript. Introduction…

Why and how to use Object.freeze to prevent mutations, what its limits are, and when to prefer alternatives like Object.seal,…