The Object seal() static method seals the object. This prevents new properties from being added and marks all the existing properties as non-configurable.

    
    const account = {
        amount: 100,
        customer: "Bill Smith"
    }

    Object.seal(account);

    // silently fails unless in strict mode then throws error
    account.location = 'Detroit';

    console.log(account.location);
    // undefined