TypeScript 6.0

TypeScript 6.0 is the last JavaScript-based release before the Go-native port. It tightens default type-checking, introduces a migration flag, deprecates legacy features, and improves union-type performance.

• Strict null checks on by default — strictNullChecks and noImplicitAny enabled for all new tsc --init projects; existing projects unaffected unless they opt in
• --migration flag — tsc --migration produces a per-file report of every change needed to move a 5.x project to 6.0 defaults, with specific line annotations
• Deprecations for legacy features — outFile, --target ES5, and namespace-based module declarations are deprecated ahead of removal in the Go-native 7.0
• Union-type checker speed — projects with union types exceeding fifty members see checker performance improvements of 15–25%

Install npm install typescript@latest.