Proposal
Adding a utility type for discriminated unions to select specific types using discriminator value.
Example:
export type DiscriminateUnion<T, K extends keyof T, V extends T[K]> =
T extends Record<K, V> ? T : never
export type T1 = { type: 'title', data: string } | { type: 'email', data: string } | { type: 'number', data: number } | { type: 'file': data: { url: string }}
// T2 is "{ type: 'title', data: string }"
export type T2 = DiscriminateUnion<T1, 'type', 'title'>
// T3 is "{ type: 'file': data: { url: string }"
export type T3 = DiscriminateUnion<T1, 'type', 'file'>
// T4 is "{ type: 'title', data: string } | { type: 'email', data: string }"
export type T4 = DiscriminateUnion<T1, 'type', 'title' | 'number''>
sindresorhus / type-fest
A collection of essential TypeScript types
14.2k
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