Creating custom objects in JavaScript

I always assumed JavaScript had the ability to create custom objects but only bothered learning how to do so recently. Turns out it's incredibly easy to create custom "objects" with parameters.

function CustomObject(a, b) {
    this.a = a;
    this.b = b;
    this.c = a + b;
    this.print = printParams;
}

function printParams() {
    alert(this.a + ',' + this.b + ',' + this.c);
}

var obj = new CustomObject(2, 3);
obj.print();

Easy.