"baseUrl" and "paths"

[cspotcode]

We have a canned response on the Typescript Discord for questions about "paths", called "paths are not magic" which I think is helpful to properly understand "baseUrl" and "paths" in node.

The paths and baseUrl compiler options don't cause any remapping of imports paths, they only inform TS of existing mappings, which you'll have to setup with some other tool.

baseUrl is a pretty well-supported option (e.g. using the NODE_PATH environment variable with node or resolve.modules with webpack).
paths can be trickier to setup, (especially with node), and you may find it to not be worth the effort.

You can use tsconfig-paths if you really want to change node's module resolver to follow path mappings from your tsconfig.json. You have many different options; pick the one that fits your project:

ts-node -r tsconfig-paths/register index.ts

# or...
node -r ts-node/register -r tsconfig-paths/register index.ts

# or NODE_OPTIONS, which also works automatically in worker_threads and child_processes
NODE_OPTIONS='-r ts-node/register -r tsconfig-paths/register' node ./index.ts

# Any of the above can be combined with TS_NODE_PROJECT if you need to specify which tsconfig.json to use
TS_NODE_PROJECT=./tsconfig-alternate.json ts-node index.ts

Or specify it in your tsconfig.json

{
  "ts-node": {
    "require": ["tsconfig-paths/register"]
  },
  "compilerOptions": { // ...

[cspotcode]

I created this post as an FAQ when users need help setting up "paths" mappings on node. If any of the above is confusing, please comment here and I'll update the post to clarify.