How to use ts-node esm loader with npx?

[Maxim-Mazurok]

A follow-up to #1007 (comment) question:

Is there any way to use ts-node esm loader with npx?
I was using this: npx -y ts-node --project ./tools/tsconfig.json ./tools/not-ignored-files.ts
Now I'm stuck with npx -y cross-env TS_NODE_PROJECT=\"tools/tsconfig.json\" node --loader ts-node/esm --experimental-specifier-resolution=node which requires devs to install project deps before running the script.

Perhaps, you could make npx -y ts-node/esm ... available?

Or is there any way I can specify something like --loader npx:ts-node/esm?...

npx --package=ts-node --call "node --loader ts-node/esm --experimental-specifier-resolution=node ./tools/not-ignored-files.ts" also didn't work for me.

[cspotcode]

I think the problem is that npx will install and run an executable into a non-local location controlled by npx, but the working directory is local. Node's --loader flag attempts to import the loader, which will be done locally unless it is an absolute path.

This is why the following:

npx --package ts-node node --loader ts-node/esm ./example.ts

Will raise an error Cannot find package 'ts-node'. ts-node cannot be found in the working directory.

We have a ticket for this: #1258

That ticket proposes the addition of a new executable: ts-node-esm which can be used as follows:

npx --package ts-node ts-node-esm ./example.ts

[Maxim-Mazurok]

Good point, looks like I can do something like this if I really want to:

npx --package ts-node@10.2.1 --call "node --loader ~/.npm/_npx/1bf7c3c15bf47d04/node_modules/ts-node/esm.mjs ...

But I probably will wait for that ticket to be closed.

I was hoping that there's some smart way to run node in the "npx context" or something...

[cspotcode]

Yeah, I guess the problem is you either have the wrong working directory for --loader ts-node/esm or the wrong working directory for your script, ./example.ts

For what it's worth, that ticket is one of our simpler ones, which is why I have been focused on other tickets instead, hoping someone will send a pull request. It seems like many people want it but not enough to implement it.

[sastraxi]

For what it's worth, I experienced the same error trying to use node --loader ts-node/esm with "type": "module" in a yarn 3 workspace. I also had "ts-node": "^10.4.0" in devDependencies.

Cannot find package 'ts-node'

For my particular solution, tsc-watch --onSuccess="node ..." was a viable strategy, so I never figured out how to solve it, sadly. Just putting my results here hopefully to reduce some frustration for any other dev coming up against the same.

[Maxim-Mazurok]

Was npx involved? This doesn't seem to be related otherwise...

[sastraxi]

It's not directly related, but yarn versions 2 and above do very different things with package resolution, and my hypothesis is that the underlying mechanism is similar. This is the only relevant result that comes up from a google search, so I've put it here to help any future spelunkers.