Шаблонные строковые типы

type Field = "name" | "age";
type EventName = `${Field}Changed`;

type Lang = "ru" | "en";
type Section = "home" | "profile";
type Key = `${Lang}.${Section}`;

type UserKey = `user:${string}`;

type A = Uppercase<"getUser">;
type B = Capitalize<"profile">;

type Getter<K extends string> = `get${Capitalize<K>}`;
type NameGetter = Getter<"name">;

type Lower = Lowercase<string>;

type PropEvents<T> = {
  [K in keyof T as `on${Capitalize<string & K>}Changed`]:
    (value: T[K]) => void;
};
type UserEvents = PropEvents<{ name: string; age: number }>;

type FieldOf<E> = E extends `${infer K}Changed` ? K : never;
type F = FieldOf<"nameChanged">;

type Model = { name: string; age: number };
type Watcher<T> = {
  on<K extends keyof T & string>(event: `${K}Changed`, cb: (value: T[K]) => void): void;
};

type Route = `/users/${number}`;

type Hex = `#${string}`;
const color: Hex = "red";

type OrderId = `ord_${string}`;
function load(id: OrderId) {}

type EventName<T extends string> = `${T}:changed`;
type UserEvent = EventName<"user">;

type Route = `/${string}/${number}`;
declare function navigate(route: Route): void;