Loader written in TypeScript not working when in node_modules

[inad9300]

Bug report

What is the current behavior?
Referencing a loader written in TypeScript works just as expected, except when the loader's TypeScript file is inside node_modules.

If the current behavior is a bug, please provide the steps to reproduce.

1. Write a simple loader using TypeScript.
2. Reference that loader from a webpack configuration file and see it working.
3. Move that loader to the node_modules directory and change the path in the webpack file to point to the new location.
4. See it fail with SyntaxError: Cannot use import statement outside a module, as webpack fails to interpret the file as TypeScript.

What is the expected behavior?
TypeScript webpack loaders should work even when placed in a directory named "node_modules", just the same as they work from any other directory.

Other relevant information:
webpack version: 5.35.1 / 4.6.0 (CLI)
Node.js version: 14.16.0
Operating System: macOS
Additional tools: ts-loader 9.1.1, ts-node 9.1.1, TypeScript 4.2.4

[alexander-akait]

See it fail with SyntaxError: Cannot use import statement outside a module, as webpack fails to interpret the file as TypeScript.

No related to webpack

[alexander-akait]

Ensure loaders can be loaded even when inside node_modules, or provide documentation tip on how to enable this (e.g. through ts-node's TS_NODE_IGNORE environmental variable)

webpack is not typescript compiler, sorry, we will not support this, you need compiler ts to js, please read my answer again

Document this feature

it is not feature, it is side effect because you use webpack.config.ts and install ts-node

Provide type definitions for loaders (currently lacking in webpack, as far as I can tell)

we are working on it #13164

[inad9300]

For what reason do you then support writing webpack configuration files in TypeScript? I find it only natural that this capability is added to loaders, extending the safety and leading to more consistency.

I have another question: have you discussed this with any of your colleagues before putting it down? I am sorry if this is not appropriate, but I feel like I haven't been taken very seriously throughout our discussion, ever since you quickly closed the original issue without even an opportunity to give an answer to your initial claim.

[alexander-akait]

Because we are not typescript compiler, please read my answer again, we can't compile ts to js, you can use ts-node for running your projects and webpack will support require/import for ts as you want

[inad9300]

I understand that I need to install ts-node so that webpack can interpret TypeScript-based configurations. I also know that I can rely on this because it is documented here. And I know as well that I can directly import loaders written in TypeScript from a webpack.config.ts file, as I indicated already in my very first message. Yet you said "you shouldn't rely on this behavior". Which is what prompted me into asking you to turn the bug report into a feature request, because I won't use the feature if I am told that it is not to be relied upon.

With regards to my second question, should I understand the absence of an answer as an actual answer? It'd be nice to get feedback from other contributors, if possible...

[alexander-akait]

You can rely on ts-node behavior

But you shouldn't rely on this behavior, Node.js is JS engine. It will not work node_modules, because ts-node ignore node_modules directory by default

I mean when you run webpack make sure you use ts-node to make the behavior explicit

What do you want to hear from other contributors? This is how require/import works on Node.js