TypeScript 5.9+ Knowledge Patch
Claude's baseline knowledge covers TypeScript through 5.8. This skill provides features from 5.9 (May 2025) onwards.
Source: https://devblogs.microsoft.com/typescript/
<!-- APPEND NEW VERSIONS BELOW THIS LINE -->5.9
| Feature | What to know |
|---------|-------------|
| import defer | import defer * as ns from "mod" — defers module execution until first property access. Namespace imports only. Requires --module preserve or esnext. |
| --module node20 | Stable pinned option for Node.js 20. Implies --target es2023. |
| ArrayBuffer breaking change | ArrayBuffer is no longer supertype of TypedArray. Fix: use Uint8Array<ArrayBuffer>, access .buffer, or update @types/node. |
| Type argument inference | Generic type inference fixes may introduce new errors from "leaked" type variables. Fix by adding explicit type arguments to generic function calls. |
TypeScript 7 (Native Port)
| Topic | What to know |
|-------|-------------|
| Versioning | TS 6.0 = last JS release (no 6.1). TS 7.x = native Go rewrite (tsgo). Repo: microsoft/typescript-go |
| Install | npm install -D @typescript/native-preview → npx tsgo |
| TS 6/7 breaking changes | --strict on by default, --target es5 removed, --baseUrl removed, --moduleResolution node10 removed |
| Migration tool | npx @andrewbranch/ts5to6 --fixBaseUrl / --fixRootDir |
| Full details | See references/typescript-7-transition.md |