What's actually new in JavaScript (and what's coming next)

A comprehensive walkthrough of ES2025 and upcoming ES2026 JavaScript features. ES2025 shipped iterator helpers (lazy .map/.filter/.take on iterators), new Set methods (union, intersection, difference), JSON modules with import attributes, Promise.try, RegExp.escape, and Float16Array. ES2026 brings the `using` keyword for automatic resource cleanup, the long-awaited Temporal date API replacing Date, import defer for lazy module evaluation, Math.sumPrecise for accurate float summation, Uint8Array base64/hex methods, Error.isError for cross-realm error checking, Iterator.concat, Map.getOrInsert, Array.fromAsync, and JSON.parse source text access. The post also covers the TC39 proposal process, what didn't make it (decorators, pipeline operator, pattern matching), and includes a ready-to-use system prompt snippet to guide AI coding assistants toward these modern APIs instead of outdated patterns.