ESM in NodeJS

To enable es module system in nodejs, it's not as simple as enabling the --experimental-modules flag.

You need:

• use .mjs file format to hint as a es module or at the nearest package.json, specify "type": "module"
• use import statement to "require" the module file -> meaning your main file also need to be a .mjs file.
• to replace all "require" and "module.exports" in .mjs file to import.
  • as an escape hatch, you can use module.createRequire
  • see https://nodejs.org/api/esm.html#esm_no_code_require_code_code_exports_code_code_module_exports_code_code_filename_code_code_dirname_code
• es modules import file must specify extension, .mjs (es modules), .cjs (commonjs) or .js (depends on nearest package.json#type).
• for commonjs to import es modules, the only way is to use dynamic import import().