Where does the function get its variables from?

Question

JavaScript

var users = [{
  name: "Вася",
  surname: 'Иванов',
  age: 20
}, {
  name: "Петя",
  surname: 'Чапаев',
  age: 25
}, {
  name: "Маша",
  surname: 'Медведева',
  age: 18
}];


function byField(field){
  return function (a,b){
    return a[field] > b[field] ? 1 : -1;
  }
}

users.sort(byField('name'));
users.forEach(function(user) {
  alert( user.name );
});

This code works, but where does the nested function in the byField function take the variables a and b if for byField = window, and for the nested function - byField(). Does where the function is called from affect the ? After all, somehow a and b with sort() were passed to byField()

Answer 1

but where does the nested function in the byField function take the variables

you call the sort function and give it this "nested" function as an argument. Functions in JS are the same objects as numbers, strings, etc.