Module resolution with tsc and ts-node

CommonJS require

When using 'require' in typescript source code then this is behavior:

• tsc expects '.cjs' or '.js' in suffix of referenced file. It can not resolve '.ts' or '.cts' . See main-require-cjs.cts
• ts-node does expect '.ts' or '.cts' and can not resolve .cjs,.js . See main-require-cjs.cts

ESM import

When using 'import' in typescript source code, then tsc and ts-node behave the same way. The ESM loader of ts-node needs to be used ( --esm flag ). However when using import syntax for commonJS modules (.cts , .cts ) , you can only import the default export. See main-import.mts.

For node 20 there is another problem. Unlike with node 18 it is not possible to use ts-node --esm <file> to resolve esm modules. Instead you need to use workarkound node --loader ts-node/esm ./src/main-import.mts See TypeStrong/ts-node#1997