Description
As per this new update to NodeJS:
The new flag --experimental-detect-module can be used to automatically run ES modules when their syntax can be detected. For “ambiguous” files, which are .js or extensionless files with no package.json with a type field, Node.js will parse the file to detect ES module syntax; if found, it will run the file as an ES module, otherwise it will run the file as a CommonJS module. The same applies to string input via --eval or STDIN.
We hope to make detection enabled by default in a future version of Node.js. Detection increases startup time, so we encourage everyone — especially package authors — to add a type field to package.json, even for the default "type": "commonjs". The presence of a type field, or explicit extensions such as .mjs or .cjs, will opt out of detection.
https://nodejs.org/en/blog/release/v21.1.0#automatically-detect-and-run-esm-syntax
We should add a link to that document and explain that having type="commonjs" will ensure faster parsing time when using the auto-module-detection flag.