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PropertyKey

With dynamic property keys we've only used the string type so far, and most of the time, that's all you need. However, JavaScript also supports number and symbols as property keys. TypeScript actually has a built-in type called PropertyKey that represents all possible property key types:

// this is a built-in type
type PropertyKey = string | number | symbol;

A symbol is a unique and immutable data type that may be used as an object property name. It's kinda like a string, but it's guaranteed to be unique.

So, instead of:

type InfrastructureTags = {
  [key: string]: any;
};

We can allow number and symbol keys (the JS default) like this:

type InfrastructureTags = {
  [key: PropertyKey]: any;
};

const janesServer: InfrastructureTags = {
  name: "Jane's Server",
  1: 420,
  [Symbol("role")]: "Admin",
};

To read or write a symbol-keyed property, use the symbol itself with bracket notation. Dot notation won't work.

const ROLE = Symbol("role");
const user = { [ROLE]: "Admin" };
user[ROLE]; // "Admin"
// user.ROLE; // undefined

Assignment

New optional security features were added to Support.ai preferences. Management wants all mail users to enable at least one security method.

Complete the isSecure function. It takes a MailPreferences as input and returns a boolean.

If the preferences enable either two-factor authentication or biometric lock, return true.
Otherwise, return false.