Ways of exports and imports modules using CommonJS

exports module

First way, object using module.exports

module.exports = {
  sum: function(a,b){
     return a + b;
  },
  sub: function(a,b){
    return a - b; 
  }
  
}

second way, only with name reference:

function sum(a,b) {
   return a + b;
}

function sub(a,b) {
   return a - b;
}

module.exports = { 
  sum, sub 
} 

Thrid, using object with exports.name: 

exports.sum = function(a,b){
     return a + b;
}

exports.sub = function(a,b){
     return a - b;
}

import module

First way, create a variable (const) and using variable.function or variavel.property

const myModule = require('./myModule');
console.log(myModule.sum(1,1));

Second way, using destructing to import specific functions and property:

const { sum }  = require('./myModule');
console.log(sum(1,1));

Third way, import and handle the function in the same line. PS: It only works if the exports be a function. 

const myModule = require('./myModule')(1,1);
console.log(myModule);