Cannot import extensionless

[shir0u]

If I include the .ts extension, typescript will complain:

TS2691: An import path cannot end with a '.ts' extension

If I don't include the .ts extension, ts-node will complain:

throw new ERR_MODULE_NOT_FOUND(
          ^
CustomError: Cannot find module

Why is this? Why does it work fine for tsc but not ts-node?

[cspotcode]

It doesn't work fine for tsc though, since you get that error.

https://devblogs.microsoft.com/typescript/announcing-typescript-4-7-beta/#type-in-package-json-and-new-extensions

Relative import paths need full extensions (we have to write import "./foo.js" instead of import "./foo").

TSC's rule is that it has to be the emitted extension, so it has to be .js. ts-node does the right thing to make this work.

[shir0u]

But tsc (4.6.3) compiles fine though and understands that the extensionless means .ts in ts file, and when compiled will append .js extension.

I see that you mentioned a beta version, that's good to know for future proof. Thanks I got the answer now 👍

[cspotcode]

Neither of those are correct, actually:

a) tsc (4.6.3) does not append the .js extension.

b) the behavior I described predates the beta

You can prove this for yourself. Put a variety of imports in a .ts file, compile them, and check the output .js file. See if any extensions have been added, removed, or rewritten.

[shir0u]

hmm maybe I was being confused with a bundler instead of using tsc directly. Thanks for the prompt reply and correction, appreciate it.