Document File name has a '.js' extension - stripping it

[sguillia]

TypeScript Version: 4.2.0-dev.20201211

Search Terms: typescript File name has a '.js' extension - stripping it

Code

https://github.com/sguillia/ts-repro-III

other.ts

import * as index from "./index.js"

index.ts

export { }

Compile with:

tsc other.ts --traceResolution

Expected behavior:

Does not compile?

Actual behavior:

$ tsc other.ts --traceResolution
...
File name '/path/to/ts-repro-III/index.js' has a '.js' extension - stripping it.
...

This document is very good:
https://www.typescriptlang.org/docs/handbook/module-resolution.html

But it doesn't talk about resolution of modules with their extensions.

The actual behavior is fine but I did not manage to find its documentation

Same issue for jsx

$ tsc other.ts --traceResolution
...
File name '/path/to/ts-repro-III/index.jsx' has a '.jsx' extension - stripping it.
...

Would it be possible to document

• which extension are trimmed?
• what look-ups are performed based on the file name with extension stripped?

Playground Link: https://github.com/sguillia/ts-repro-III

Related Issues: no