Question

For whatever reason I’m getting TypeError: Object #<Num> has no method 'getNumber' when creating numberOne as an instance of Num

function Num(n) {
    var number = n;
    var getNumber = function() {
        return number;
    };
}

var numberOne = new Num(5);
console.log(numberOne.getNumber());

Answer 1

You are creating a local variable called getNumber without attaching it to the object. Either give it to the object, or put it on the prototype:

this.getNumber = function() {

or

function Num(n) {
    this.number = n;
}

Num.prototype.getNumber = function() {
    return this.number;
}

If you are creating lots of objects, you probably want to put getNumber on the prototype so it doesn’t get added to the object every single time one gets created.