Type Alias DiscriminatedUnion<Tag, Map>

DiscriminatedUnion: { [K in keyof Map & string]: { [P in Tag]: K } & Map[K] }[keyof Map & string]

Build a discriminated union from a tag key and a mapping object.

Type Parameters

Tag extends string
Discriminator property name
Map extends Record<string, any>
Mapping of discriminator values to object shapes

Remarks

Creates a union of object types where each member is tagged with a literal discriminator value derived from the mapping keys.

Example

type AnimalMap = {
  cat: { meows: boolean };
  dog: { barks: boolean };
};

type Animal = DiscriminatedUnion< 'type', AnimalMap >;
// { type: 'cat'; meows: boolean } | { type: 'dog'; barks: boolean }