Node 24 overwrites a 34-character type annotation with 34 spaces to keep columns exact

Count the characters on the line that failed. It reads `const describe = (invoice: Invoice, options: Readonly<Record<string, string>>): string => invoice.id.toUpperCase() + options.locale.trim();` ^[4], and the post reports it is exactly 139 characters in both the file on disk and the file Node executed ^[7]. `options.locale.trim()` starts at column 118, which puts the `t` of `trim` at column 133 ^[1]. Node's stack frame printed `cols.ts:3:133` ^[5].

Blanking is why. "annotations are overwritten in place with the same number of blanks, never removed," the post's author wrote ^[8]. `: Invoice` is nine characters and the executed copy has nine spaces in its place; `: Readonly<Record<string, string>>` is thirty-four, and so is the gap ^[6]. Those two annotations account for 43 of the line's 139 characters ^[2]. The caret lands under the right character with no source map involved ^[9].

Node bundles Amaro, a thin wrapper around swc's TypeScript stripper compiled to WebAssembly, which parses a `.ts`, `.mts` or `.cts` file, blanks out everything that exists only for the type checker, and hands the result to V8 ^[10]. Node never looks for `tsconfig.json`: not `paths`, not `experimentalDecorators`, not `target` ^[11]. It skips checking and resolution entirely ^[12]. Overwriting characters cannot generate code, so any TypeScript feature that has to emit JavaScript is out of scope by construction ^[13].

That is visible in the author's four-file service, which installs nothing at runtime and keeps three scripts: `dev` is `node --watch server.ts`, `test` is `node --test`, and `check` is `tsc --noEmit` ^[16]. The compiler still runs, only out of the check script now. With `tsconfig` ignored, aliasing moves into the `imports` field of `package.json`, mapping `#src/*` to `./src/*`, and the domain module imports `#src/money.ts` with the extension of the file that is actually on disk ^[16][17]. The author flags that specifier in passing: "Hold that thought; it comes back later as an error message." ^[17]

The report covers one four-module service and the two scripts that publish the author's blog ^[18]. For the result to transfer, three things have to be true of your code. Nothing depends on `target` downleveling or `experimentalDecorators` ^[11]. Every import specifier already names a file that exists on disk with its real extension ^[12]. And someone runs `tsc --noEmit` somewhere a failure blocks a merge ^[16]. The post says the approach "refuses five specific things, and one of them fails in a way that will cost you an afternoon if nobody tells you first" ^[18]; the available text sets out the three consequences above and breaks off inside `parseNewInvoice` ^[19].

`process.features.typescript` reports `"strip"` on the Node 24 default, `"transform"` under `--experimental-transform-types`, and `false` under `--no-strip-types` ^[14]. That last flag turns `.ts` back into an unknown extension, which is how the author proves a deployment is running compiled output instead of stripping on the fly ^[15]. `--experimental-strip-types` has been unnecessary since Node 23.6, and the author reported typing it anyway, "for a week out of muscle memory, like a password for an account that no longer exists" ^[2][3].