javascript - Is there any point to use getters/setters for an object?

Question

It seems to me that using getters and setters for an object inside a class has no point to it. As I understand it, get/set is useful because it prevents someone outside the class changing something that shouldn't be changed or changing it to something it shouldn't be. However it seems pointless for objects. For example, I have a person with an address, I want to prevent editing the address, you can only view it:

class Person{
    constructor(name, address){
        this._name = name;
        this._address = address;
    }

    get address(){
        return this._address;
    }
}

let bob = new Person("bob", {
    street: "123 Main Street",
    city: "Los Angelos",
    state: "California"
});

But then you can still edit it like this:

let address = bob.address;
address.state = "New York";

To prevent this, I would think that you have to return a copy of the object instead of the reference. However, as far as i know, there is no standard way to deep clone an object. So you either have to shallow clone it, which seems not ideal if you have lots of nested references, or just return the reference to the object, which can be edited.

Am I missing something here?

Answer 1

Consider this class.

class Test {
    constructor(val) {
        this._foo = val;
    }

    set foo(val) {
        throw new Error("It's not possible to change the foo property!")
    }

    set boo(val) {
        console.log("setting _boo")
        this._boo = val;
    }

    get foo() {
        console.log("getting _foo");
        return this._foo;
    }
}

try {
    let test = new Test('foooooo');
    test.boo = "booooo";
    console.log(`foo: ${test.foo}`);
    test.foo = "bar";
} catch (e) {
    console.log(e);
}