TypeScript 6.0 is your final warning

TypeScript 6.0 has been released as the last version built on its JavaScript codebase, serving as a transition before TypeScript 7.0 introduces a Go-based compiler with native speed and multi-threaded type checking. Key changes include strict mode enabled by default, module defaulting to esnext, target floating to the current ES spec (es2025), and types defaulting to an empty array — a change that may break many projects but promises 20–50% speed improvements. New features include built-in Temporal API types and Map.getOrInsert support. Several legacy options like outFile, baseUrl, and AMD/UMD/SystemJS targets are deprecated or removed. The newsletter also covers pnpm 11 beta, Zero 1.0 stable release, a React useState closure gotcha, and various other JavaScript ecosystem links.