Modernize TypeScript
Operational guides for TypeScript: the TypeScript 5 upgrade hub, the 4-to-5 migration path, incremental JavaScript-to-TypeScript adoption, and fixing build errors.
Last verified · Updated May 22, 2026
TypeScript's releases tighten checking and reshape compiler flags. This hub links the TypeScript 5 upgrade path, incremental JavaScript-to-TypeScript adoption, and the workflow for diagnosing the build errors those changes surface.
What this covers
Start at the TypeScript 5 upgrade hub for the full breaking-change picture, then follow the TypeScript 4 to 5 path if you are upgrading an existing project, 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
- 5.xcurrentactivereleased 2023-03-16
- 4.xmaintenancereleased 2020-08-20
TypeScript migration paths
Frequently asked questions
Which TypeScript version should I target?
TypeScript 5.x is the current line and the recommended target. The 4-to-5 jump is mostly mechanical: drop removed flags, update moduleResolution, and decide on a decorator model. Upgrading within 5.x is rarely breaking beyond stricter type checks.