privacy-check.js

console.log(dog.nombre) // undefined

with (dog) {
    try {
        console.log(nombre) // error
    } catch(error) {
        console.log('nombre is not defined even inside the with (dog)');
    }
}

dog.setName = function () {
    console.log(nombre);
}

try {
    dog.setName(); // error
} catch(error) {
    console.log('nombre is not defined even if the function is replaced');
}