type Person = { age: number; name: string; alive: boolean };
type Age = Person["age"];
// type Age = number
type I1 = Person["age" | "name"];
// type I1 = string | number
type I2 = Person[keyof Person];
// type I2 = string | number | boolean
type AliveOrName = "alive" | "name";
type I3 = Person[AliveOrName];
// type I3 = string | booleanUnions
When accessed on unions, it will return all possible types of the property from all members:
export type Event =
| {
type: "click";
event: MouseEvent;
}
| {
type: "focus";
event: FocusEvent;
}
| {
type: "keydown";
event: KeyboardEvent;
};
type EventType = Event["type"];
// type EventType = "click" | "focus" | "keydown"