const config = { api: 'v1', timeout: 5000 };
Object.seal(config);
const settings = { theme: 'dark', lang: 'en' };
Object.freeze(settings);
config.api = 'v2';
config.retries = 3;
settings.theme = 'light';
settings.debug = true;
console.log(config.api);
console.log(config.retries);
console.log(settings.theme);
console.log(settings.debug);
Ответ: v2 undefined dark undefined
JavaScript test | #JavaScript & Max