How to call functions with parameters within a nested function?

Question

Let's say I have a nested function named countries and I want to call two functions with one named Russia with parameter named cities1 and another named China with parameter named cities2 within the function countries. How do I call the two functions with parameters within a nested function?

function countries() {
  function Russia(cities1) {
    var totalpop1 = cities1 * (10 ** 6);
    //each city has a population of 10^6 people
    return totalpop1;
  }

  function China(cities2) {
    var totalpop2 = cities2 * (10 ** 6);
    //each city has a population of 10^6 people
    return totalpop2;
  }
  var result = totalpop1 + totalpop2;
  return result;
}

Answer 1

I think you can use an Object (like a Class).

What about the code below?

 var countries = { getRussia: function(cities1) { var totalpop1 = cities1 * (10 ** 6); //each city has a population of 10^6 people return totalpop1; }, getChina: function(cities2) { var totalpop2 = cities2 * (10 ** 6); //each city has a population of 10^6 people return totalpop2; }, getTotal: function(pop1, pop2) { var result = this.getRussia(pop1) + this.getChina(pop2); return result; } } var div = document.querySelector("#result"); div.innerHTML = countries.getTotal(1, 4); 

 <div id="result"></div> 

But if you really want to call nested funcions you could use closures:

function countries() {
    return function(cities1) {
    var totalpop1 = cities1 * (10 ** 6);

    return function(cities2) {
        var totalpop2 = cities2 * (10 ** 6);

      return totalpop1 + totalpop2;
    }
  }
}

var div = document.querySelector('#result');

div.innerHTML = countries()(1)(4);