ts-node and custom loaders

Question

Is it possible to use ts-node and a custom loader? In the docs I only see a way to enable esm compatibility.

ts-node --esm my-file.ts

I am trying to use a custom loader for testing an ESM module but I don't want to use node to compile each time since this is for a test suite. The way to use (multiple) loaders in node is like so

node --loader=esm --loader=testdouble my-file.js

user_438273 · Answer

Sure: Just use ts-node/esm as the loader value. This is documented as an environment variable in ts-node's README:

Or, if you require native ESM support:
NODE_OPTIONS="--loader ts-node/esm"
This tells any node processes which receive this environment variable to install ts-node's hooks before executing other code.

Be sure to understand:

the caveats of this loader: GitHub — TypeStrong/ts-node#1007
how the Loader API works in Node: Node.js — API > ESM > Loaders

ts-node and custom loaders

1 Answers