It does not do any type checking. You have to run tsc with noEmit separately. If you run `bun run foo.ts`, it just ignores all type annotations. It is transpiled to JS internally by removing the types (or it skips the types while parsing). While doing that, it keeps track of the original source locations. If you see some stack trace, you get the original location in the ts source.

Running tsc with noEmit is pretty much the standard in the frontend as well, as the TS is bundled by esbuild/rollup directly.