Javascript array, building from a set of variables

You could create an array of the car instances and use the map function

console.log(
  [golf, sentra, _328i, gallardo, corniche].map((car) => car.maker)
)

There are a lot of solutions to that. First, you need to make an array with all your cars, and then use a method to iterate on each car to get the car maker.

Here two examples:

var Car = function (maker, type, model) {
  this.maker = maker;
  this.type = type;
  this.model = model;
}

Car.prototype.year = 0;

var golf = new Car ('VW', 'Hatchback', 'Golf');
var sentra = new Car ('Nissan', 'Sedan', 'Sentra');
var _328i = new Car ('BMW', 'Convertible', "328i");
var gallardo = new Car ('Lamborghini', 'Convertible', "Gallardo", 2020);
var corniche = new Car('Rolls Royce', 'Sedan', "Corniche");

golf.year = 2015;
sentra.year = 2010;
_328i.year = 2019;
gallardo.year = 2020;
corniche.year = 1998;

var cars = [golf, sentra, _328i, gallardo, corniche]
var carsMakers = []

for(var i = 0; i < cars.length; i++) {
  var c = cars[i]
  carsMakers.push(c.maker)
}
console.log(carsMakers)

var carsMakers2 = cars.map(function(c) { return c.maker });
console.log(carsMakers2)

Just like the map approach but using Array.prototype.from:

var Car = function (maker, type, model) {
this.maker = maker;
this.type = type;
this.model = model;
}
var golf = new Car ('VW', 'Hatchback', 'Golf');
var sentra = new Car ('Nissan', 'Sedan', 'Sentra');
var _328i = new Car ('BMW', 'Convertible', "328i");
var gallardo = new Car ('Lamborghini', 'Convertible', "Gallardo");
var corniche = new Car('Rolls Royce', 'Sedan', "Corniche");

Car.prototype.year = 0;

golf.year = 2015;
sentra.year = 2010;
_328i.year = 2019;
gallardo.year = 2020;
corniche.year = 1998;

// Solution here
const makersList = Array.from([golf, sentra, _328i, gallardo, corniche], car => car.maker );

// should print an array of makers string names
console.log(makersList);