import { type MergeExclusive } from "https://deno.land/x/actionify@0.3.0/src/deps/types.ts";
Create a type that has mutually exclusive keys.
This type was inspired by this comment.
This type works with a helper type, called Without
. Without<FirstType, SecondType>
produces a type that has only keys from FirstType
which are not present on SecondType
and sets the value type for these keys to never
. This helper type is then used in MergeExclusive
to remove keys from either FirstType
or SecondType
.
Examples
Example 1
Example 1
import type {MergeExclusive} from 'type-fest';
interface ExclusiveVariation1 {
exclusive1: boolean;
}
interface ExclusiveVariation2 {
exclusive2: string;
}
type ExclusiveOptions = MergeExclusive<ExclusiveVariation1, ExclusiveVariation2>;
let exclusiveOptions: ExclusiveOptions;
exclusiveOptions = {exclusive1: true};
//=> Works
exclusiveOptions = {exclusive2: 'hi'};
//=> Works
exclusiveOptions = {exclusive1: true, exclusive2: 'hi'};
//=> Error
definition: (FirstType | SecondType) extends object ? (Without<FirstType, SecondType> & SecondType) | (Without<SecondType, FirstType> & FirstType) : FirstType | SecondType