Progress on TypeScript 7 – December 2025
Source: Hacker News
December 2nd, 2025
Earlier this year, the TypeScript team announced that we’ve been porting the compiler and language service to native code to take advantage of better raw performance, memory usage, and parallelism. This effort (codenamed “Project Corsa”, soon “TypeScript 7.0”) has been a significant undertaking, and we’ve made big strides in the past few months. Below are the latest updates.
Editor Support and Language Service
TypeScript’s native previews are fast, stable, and easy to use today – including in your editor. The language service (the engine behind editor features) is a core part of the native port effort and can be tried out via the Visual Studio Code Marketplace, which updates daily.
Key editor features now available:
- Code completions (including auto‑imports)
- Go‑to‑definition / go‑to‑type‑definition / go‑to‑implementation
- Find‑all‑references
- Rename
- Quick info / hover tooltips
- Signature help
- Formatting
- Selection ranges
- Code lenses
- Call hierarchy
- Document symbols
- Quick fixes for missing imports
These operations work in any TypeScript or JavaScript codebase, including projects that use project references. The language service has been re‑architected for reliability and shared‑memory parallelism, delivering faster load times, lower memory usage, and a more responsive editing experience. If needed, the extension lets you toggle between VS Code’s built‑in TypeScript experience and the new native preview.
Compiler
The native‑ported compiler is also progressing rapidly. Nightly preview builds are published under the npm package @typescript/native-preview. Install it with:
# local dev dependency
npm install -D @typescript/native-preview
# global install
npm install -g @typescript/native-previewThe package provides a tsgo command that mirrors tsc; both can be used side‑by‑side.
Type‑checking parity
Out of ~20 000 compiler test cases, only 74 differ between TypeScript 6.0 and the native preview (mostly incomplete work or intentional changes). This means you can confidently use TypeScript 7 today to type‑check your project.
Build features
Incremental builds, project references, and --build mode are fully ported and dramatically faster thanks to native code performance and shared‑memory parallelism.
# Running tsc in --build mode...
tsc -b some.tsconfig.json --extendedDiagnostics
# Running the new compiler in --build mode...
tsgo -b some.tsconfig.json --extendedDiagnosticsEven without --incremental, full builds often see close to a 10× speedup over the 6.0 compiler.
Sample speed comparisons
| Project | tsc (6.0) | tsgo (7.0) | Δ (seconds) | Speedup |
|---|---|---|---|---|
| sentry | 133.08 s | 16.25 s | 116.84 s | 8.19× |
| vscode | 89.11 s | 8.74 s | 80.37 s | 10.2× |
| typeorm | 15.80 s | 1.06 s | 14.20 s | 9.88× |
| playwright | 9.30 s | 1.24 s | 8.07 s | 7.51× |
Expected Differences from TypeScript 5.9
While many gaps have been closed, a few caveats remain. Some are temporary issues that will be resolved before the final 7.0 release; others stem from long‑term decisions aimed at improving the default TypeScript experience.
Deprecation Compatibility
TypeScript 7.0 will remove behaviors and flags slated for deprecation in 6.0. See the list of upcoming deprecations for 6.0 on the issue tracker. Notable changes include: