es5 vs es6 cyclic dependencies

es5-add.js

const subtractModule = require('./subtract.js');

exports.countAdd = 0;

exports.add = function(n = 0) {
  exports.countAdd++;
  console.log('countAdd', exports.countAdd);

  subtractModule.countSubtract++
  console.log('countSubtract from add file', subtractModule.countSubtract);

  if (n < 20) return subtractModule.subtractfn(n + 1);
}

subtractModule.subtractfn(exports.countAdd);

es5-subtract.js

const addModule = require('./add.js');

exports.countSubtract = 0;

exports.subtractfn = function(n = 0) {
  exports.countSubtract++;
  console.log('countSubtract', exports.countSubtract);

  if (n < 20) return addModule.add(n + 1);
}

es6-add.js

import { subtractfn, countSubtract } from './subtract';

export var countAdd = 0;

export function add(n = 0) {
  countAdd++;
  console.log('countAdd', countAdd);

  countSubtract++;
  console.log('countSubtract from add file', countSubtract);

  if (n < 20) return subtractfn(n + 1);
}

subtractfn(countAdd);

es6-subtract.js

import { countAddPre, add } from './add';

export var countSubtract = 0;

export function subtractfn(n = 0) {
  countSubtract++;
  console.log('countSubtract', countSubtract);

  if (n < 20) return add(n + 1);
}