Page 9 - JavaScript

JavaScript

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Object.hasOwn vs. hasOwnProperty: Safe Property Checks Without Pitfalls

Maxim Mironjuk - April 02, 2025

obj.hasOwnProperty(key) looks harmless, but it breaks with null prototype objects and with overridden prototype methods. Object.hasOwn(obj, key) is the static, robust alternative that avoids exactly these pitfalls and should be the default choice for property checks in modern code.

JavaScript

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Array.fromAsync in Practice: Turning Async Iterables into Arrays Cleanly

Maxim Mironjuk - March 31, 2025

Anyone who has turned an asynchronous data stream into an array with manual loops and push calls knows the race conditions and the awkward error handling that come with it. Array.fromAsync solves exactly this problem: a single built in method that collects async iterables, generators and mixed promise lists in the correct order into an array.

JavaScript TypeScript

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JavaScript Nullish Coalescing and Optional Chaining Explained

Maxim Mironjuk - March 29, 2025

Nullish Coalescing (??) and Optional Chaining (?.) are the most important additions to JavaScript since ES2020. They replace fragile && chains and || fallbacks with precise, readable operators, with the crucial difference that they react only to null and undefined, not to every falsy value.

JavaScript Web Performance

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Web Share API: Native Share Dialog in JavaScript

Maxim Mironjuk - March 18, 2025

Custom share buttons hardcoded to a handful of social media platforms are outdated. The Web Share API opens the operating system's native share dialog, and the user decides which app to use: WhatsApp, Telegram, Email, Notes, or anything else. The result is better UX with less code and no dependency on third-party SDKs.

JavaScript TypeScript

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JavaScript Pattern Matching Proposal: the match Expression and Structural Matching

Maxim Mironjuk - March 16, 2025

switch/case only handles primitive equality, nested conditions quickly become unreadable, and there is no expression character at all. The TC39 Pattern Matching Proposal changes that: a match expression checks structure, type, shape, and value of an object at the same time, declaratively, exhaustively, and without a fallthrough bug.

JavaScript Design Patterns

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WeakMap and WeakSet: Private Object State Without Memory Leaks

Maxim Mironjuk - March 16, 2025

An ordinary Map used to associate objects with private state prevents those objects from ever being collected by the garbage collector as long as the map exists. WeakMap and WeakSet solve exactly this problem by only weakly referencing their keys, enabling private state that automatically disappears along with its associated object.

JavaScript Web Performance

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Web Workers in JavaScript: Mastering Multithreading in the Browser

Maxim Mironjuk - March 14, 2025

JavaScript is single-threaded, but that is not a law of nature for browser applications. Web Workers bring real multithreading to the browser: CPU-intensive calculations, file processing, encryption and AI inference run in background threads while the UI thread stays responsive and processes user interactions smoothly.

JavaScript React

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Module Federation and Micro-Frontends in JavaScript

Maxim Mironjuk - March 12, 2025

Module Federation in Webpack 5 solves what has long been the hardest problem in micro-frontend architectures: how multiple independent teams can combine their JavaScript bundles at runtime, without loading shared dependencies multiple times or sharing a central build pipeline.

JavaScript TypeScript

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JavaScript using: Explicit Resource Management with using and await using

Maxim Mironjuk - March 04, 2025

The new using keyword in JavaScript automates releasing resources when a scope is left: database connections, file handles, locks and workers are guaranteed to be cleaned up, whether the block ends normally, throws an exception, or triggers an early return.

JavaScript Web Performance TypeScript

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JavaScript Error Cause: Structured Error Handling with error.cause

Maxim Mironjuk - February 28, 2025

In JavaScript, the original error gets lost on re-throw: an Error is replaced by another one, and the context disappears. The error.cause feature from ES2022 solves exactly this problem. It allows structured error chains where each layer keeps its own context while the root error is passed through.