In this detailed announcement, Daniel Rosenwasser unveils the TypeScript Native Previews—offering a natively compiled TypeScript compiler and toolset in Go. The article covers installation, new features, ongoing limitations, and an active roadmap for developers.

Announcing TypeScript Native Previews

By Daniel Rosenwasser

This past March, the TypeScript team unveiled efforts to port the entire TypeScript compiler and toolset to native code, primarily in Go. This port has led to substantial improvements: most projects now experience over a 10x speed-up, not solely due to native code, but also thanks to shared memory parallelism and concurrency.

Public Availability & How to Try It

TypeScript Native Previews are now broadly available. Developers can preview the native TypeScript compiler through npm:

npm install -D @typescript/native-preview

This provides the tsgo executable, which is used similarly to tsc:

npx tsgo --project ./src/tsconfig.json

Currently, tsgo is separate from tsc for testing and experimentation, though future releases will streamline this.

Editor Support: Visual Studio Code

A preview VS Code extension, “TypeScript (Native Preview)”, is available via the Visual Studio Marketplace. After installing, enable it through the Command Palette (“TypeScript Native Preview: Enable (Experimental)”) or by toggling the relevant setting (typescript.experimental.useTsgo) in either the Settings UI or settings.json.

Updates, Release Cadence, and Roadmap

  • The native preview is the precursor to TypeScript 7, published nightly.
  • Extension users will receive automatic updates.
  • Issues or disruptions can be reported on GitHub, and the new language service can be disabled if needed.

Note: Native previews currently lack some stable TypeScript features, including --build, --declaration emits, downlevel targets, and some advanced editor integrations (e.g., auto-imports, find-all-references, and rename).

What’s New: Progress Since Initial Announcement

Project Names

  • Corsa: Codename for the native (TS7) codebase.
  • Strada: The JS-based TypeScript 5.8 codebase.

Type-Checking Support

  • Type-checker port: Most of the type-checker is ported; most projects should see the same errors (with some intentional changes and possible lib.d.ts differences).
  • File issues for any divergences found.
  • New features added:
    • JSX type-checking support (was previously missing).
    • Enhanced JavaScript + JSDoc checking.
JSX Checking Example (Sentry codebase)
  • With TypeScript 5.8 (Strada): about 73 seconds to type-check ~1.1M lines.
  • With tsgo (Corsa): ~6.7 seconds for similar workload (10x+ speedup).
  • Results may vary, but large projects with JSX benefit significantly from the new compilation model.
  • Further details on JSX implementation can be found in linked GitHub PRs and factory imports.

JavaScript Checking

  • Native preview supports parsing and type-checking of JavaScript via JSDoc.
  • Implementation for JS support was rewritten, leading to potential changes for some legacy JS patterns—feedback is sought for needed adjustments.

Editor Support & LSP Progress

  • Transitioning from TSServer protocol (used by Strada) to LSP for wider compatibility.
  • Basic LSP features available: errors/diagnostics, go-to-definition, and hover.
  • Completion support recently enabled (full auto-imports/advanced features pending).
  • Ongoing work on language server tests and advanced editor features: find-all-references, rename, and signature help.

API Progress

  • Early API layer implemented, enabling communication over IPC with TypeScript processes regardless of consuming language.
  • Node.js integration uses a new native Rust module (libsyncrpc) for synchronous process communication.
  • Further API development and design input are welcomed (details).

Known and Notable Differences

  • Some default settings and deprecations differ from older versions, such as node/node10 resolutions (replaced by node16, nodenext, bundler, etc.).
  • Projects using deprecated settings may see module or type declaration errors; recommended is to switch configurations or use auto-imports to resolve issues.
  • Current limitations:
    • Limited support for downlevel emit
    • JSX emit: preserves code, not transforms
    • Declaration emit unsupported
    • --build mode not available (individual projects can still be built)
    • Project reference language service features incomplete

Roadmap & What’s Next

  • Aim for more comprehensive features (including --build) and complete language service/editor capabilities by later this year
  • Nightly previews and periodic major updates planned; developers are encouraged to try the native previews and provide feedback

Happy Hacking!

— Daniel Rosenwasser and the TypeScript Team

This post appeared first on “Microsoft TypeScript Blog”. Read the entire article here