Changelog

microsoft/typescript-go · Jun 15–21, 2026 · 16 commits

Declaration emit, native preview API, and watch mode get major polish

This week tightened `.d.ts` generation, expanded the native-preview API, overhauled watch builds, and fixed crashes in tsconfig and auto-imports.

Declaration emit got several correctness fixes

.d.ts output is now more faithful in tricky export and method cases — The emitter fixed class-expression naming for CJS exports, preserved modifier order for private JS methods, removed duplicate | undefined wrapping, re-allowed nested CommonJS export assignments, and deduplicated this-assigned methods. Together these changes close a cluster of declaration-generation regressions around anonymous classes, expando patterns, and synthesized members.

Native preview API and tooling were expanded

The preview API now carries more type information with less churn — Signature objects are exposed end-to-end, client-side caching now covers symbols, types, signatures, and type lists, and cached SourceFiles keep API node tables across snapshots. Empty-string literal values are also serialized correctly, making API responses more reliable for literal types.

Editor and packaging support improved — The native preview gained Sort Imports and Remove Unused Imports commands, and package generation now includes NOTICE.txt in the main native preview artifacts.

Build watching was substantially reworked

Build mode now rides on the new fswatch/watchmanager plumbing — Watching was refactored away from timestamp tracking, changing how file/config updates and watcher races are handled. The week also included broad baseline updates to lock in the new behavior.

Stability fixes across core workflows

Several crashy edge cases were removed — Auto-import no longer crashes in the alias resolver, and tsconfig parsing no longer panics when extending an empty config file.

Filesystem and Unicode-related behavior is more predictable — Auto-import cleanup now drops stale node_modules buckets when folders disappear, and JS casing tables are pinned to generated Unicode data so casing behavior stays aligned with the repo’s Unicode version.

Other misc changes

  • Added documentation note for tsc on TypeScript 7.0 RC and later
  • Expanded tests and refreshed baselines for snapshot caching, auto-imports, declaration emit, watch mode, Unicode casing, and config parsing