Please rework the section which falsely claims that privacy can be achieved through Symbols, and that the latter can be used as well for hiding critical informations securely. It's a dangerous advice and/or misbelieve. Object.getOwnPropertySymbols already is all what it needs in order to unveil everything ...

const secretKey = Symbol("hiddenValue");

const secureObject = {
    [secretKey]: "Top Secret Info",
    publicData: "Visible to Everyone"
};

function getThisValue(key) {
  return this[key];
}
console.log(
  Object
    .getOwnPropertySymbols(secureObject)
    .map(getThisValue, secureObject)
);

And Object.getOwnPropertyDescriptors will always provide everything about an object’s structure.

const secretKey = Symbol("hiddenValue");

const secureObject = {
    [secretKey]: "Top Secret Info",
    publicData: "Visible to Everyone"
};
console.log(
  Object
    .getOwnPropertyDescriptors(secureObject)
);