Prototype is good, we want these functions on the prototype rather than the instance.
By the way which method do you like more for inheritance?
```
MyClass.prototype = {
  __proto__: ParentClass.prototype,
  someFunc: {}
};
```
or
```
MyClass.prototype = Object.create(ParentClass.prototype); // or new ParentClass();
MyClass.prototype.someFunc = function() {}
```
I tend to prefer the second one because of the controversy surrounding the use of __proto__, but I could be convinced.