Variable isCommonJS`Const`

isCommonJS: boolean = ...

Determines whether the current runtime is executing in a CommonJS environment.

Remarks

This performs multiple checks to improve reliability:

module.exports existence (primary CJS signal)
exports object presence
require function availability
__filename and __dirname variables

No single check is fully reliable across all bundlers/transpilers, so a combination is used.

Returns

true if the runtime is very likely CommonJS, otherwise false.

Example

if (isCommonJS) {
  console.log("Running in CommonJS");
} else {
  console.log("Running in ESM");
}