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Modernize TypeScript

Operational guides for TypeScript: the TypeScript 6 upgrade hub, the 5-to-6 and 4-to-5 migration paths, incremental JavaScript-to-TypeScript adoption, and fixing build errors.

Last verified · Updated May 22, 2026

TypeScript's releases tighten checking and reshape compiler defaults. TypeScript 6.0 (March 2026) flips strict, module, and target to modern defaults and is the last JavaScript-based release before the Go-native 7.0. This hub links the TypeScript 6 upgrade path, the 5-to-6 and 4-to-5 migrations, JavaScript-to-TypeScript adoption, and the workflow for diagnosing the build errors those changes surface.

What this covers

Start at the TypeScript 6 upgrade hub for the full breaking-change picture, then follow the TypeScript 5 to 6 path if you are on a recent 5.x, the TypeScript 4 to 5 path for older projects, or the JavaScript-to-TypeScript guide if you are adopting types for the first time. Each page includes a repo-inspection prompt, step-by-step migration, a test plan, and rollback guidance.

Version timeline

  • 6.0.3 — current, active (released 2026-03-23)
  • 5.x — maintenance (released 2023-03-16)
  • 4.x — maintenance (released 2020-08-20)

TypeScript migration paths

Frequently asked questions

Which TypeScript version should I target?

TypeScript 6.0 (latest 6.0.3) is the current line and the recommended target. The 5-to-6 jump is mostly about the new defaults: strict, module: esnext, target: es2025, esModuleInterop, and types: [] all change, so pin the values your build expects. The 4-to-5 jump before it is largely mechanical: drop the flags deprecated in 5.0 (removed in 6.0), update moduleResolution, and decide on a decorator model.

Should I wait for TypeScript 7.0?

TypeScript 6.0 is the last release on the JavaScript-based compiler; 7.0 is a native rewrite in Go that is close to completion. Treat 6.0 as the cleanup step: resolve every deprecation it reports (it can be suppressed with "ignoreDeprecations": "6.0", but that escape hatch is gone in 7.0) so the eventual jump to the native compiler is clean. You can preview 7.0 today via the @typescript/native-preview package.