Demo of how to use ESM modules in CommonJS module with TypeScript

Demonstrating how to use ESM-only packages node-fetch@3 and got@12 in a commonjs project. As well as using import from node:child_process.

For TS v5.0 see ts-50 branch

Running it

1. git clone https://github.com/Maxim-Mazurok/esm-in-cjs-ts-demo && cd esm-in-cjs-ts-demo
2. nvm i - make sure to use node/npm versions from "engines" section of the package.json
3. npm ci - install deps
4. npm start - compile and run
5. Observe:

   [Function: spawn]
   Fetched with node-fetch:  <ref *1> Gunzip {...
   Fetched with got:  {"login":"Maxim-Mazurok",...
   

Notes

• Need "esModuleInterop": true to resolve Module '"node:http"' has no default export error and similar
• Need "module": "Node16" or others to resolve Dynamic imports are only supported when the '--module' flag is set to 'es2020', 'es2022', 'esnext', 'commonjs', 'amd', 'system', 'umd', 'node16', or 'nodenext'.
• Need "module": "Node16" to allow using import instead of require(), resolves Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension. error in import { spawn } from "child_process";
• Need "moduleResolution": "Node16" to resolve Cannot find module 'node-fetch'. Did you mean to set the 'moduleResolution' option to 'nodenext', or to add aliases to the 'paths' option?
• Don't really need to add "type": "commonjs" in package.json because module is assumed to be commonjs unless it has "type": "module" in package.json. tsconfig doesn't seem to affect that.
• Need to use (async () => {...})() pattern to resolve 'await' expressions are only allowed at the top level of a file when that file is a module, but this file has no imports or exports. Consider adding an empty 'export {}' to make this file a module.
• Need to use dynamic imports to resolve The current file is a CommonJS module whose imports will produce 'require' calls; however, the referenced file is an ECMAScript module and cannot be imported with 'require'. Consider writing a dynamic 'import("got")' call instead. To convert this file to an ECMAScript module, change its file extension to '.mts' or create a local package.json file with { "type": "module" }
• Can't use "moduleResolution": "nodenext" with "module": "CommonJS", they need to match since TS 5.2, see https://devblogs.microsoft.com/typescript/announcing-typescript-5-2/#module-and-moduleresolution-must-match-under-recent-node-js-settings