inherits

index.js

'use strict';

const {
  Calc
} = require('./modules/util');

const calc = new Calc();

console.log('calc', Calc);

console.log('add', calc.add(2, 3));
console.log('subtract', calc.subtract(5, 3));

inherits.js

'use strict';

const {
  inherits
} = require('util');

function CalcExtend () {
};

CalcExtend.prototype.add = (n1, n2) => {
  return n1 + n2;
};


function Calc () {
};

inherits(Calc, CalcExtend);

Calc.prototype.subtract = (n1, n2) => {
  return n1 - n2;
};

module.exports = {
  Calc
};