Accessor properties get and set

Treat a property as a combination of two functions, one to get the value from it, and another one to set the value in it.

The get property of the property descriptor is a function that will be called to retrieve the value from the property.

The set property is also a function, it will be called when the property has been assigned a value, and the new value will be passed as an argument.

You cannot assign a value or writable to a descriptor that has get or set

var person = { name: "John", surname: "Doe"};
Object.defineProperty(person, 'fullName', { 
    get: function () { 
        return this.name + " " + this.surname;
    },
    set: function (value) {
        [this.name, this.surname] = value.split(" ");
    }
});

console.log(person.fullName); // -> "John Doe"

person.surname = "Hill";
console.log(person.fullName); // -> "John Hill"

person.fullName = "Mary Jones";
console.log(person.name) // -> "Mary"