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type-fest/source/if-null.d.ts

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483 BTypeScriptView Raw

1import type {IsNull} from './is-null';
2
3/**
4An if-else-like type that resolves depending on whether the given type is `null`.
5
6@see {@link IsNull}
7
8@example
9```
10import type {IfNull} from 'type-fest';
11
12type ShouldBeTrue = IfNull<null>;
13//=> true
14
15type ShouldBeBar = IfNull<'not null', 'foo', 'bar'>;
16//=> 'bar'
17```
18
19@category Type Guard
20@category Utilities
21*/
22export type IfNull<T, TypeIfNull = true, TypeIfNotNull = false> = (
23	IsNull<T> extends true ? TypeIfNull : TypeIfNotNull
24);

1	`import type {IsNull} from './is-null';`
2
3	`/**`
4	An if-else-like type that resolves depending on whether the given type is `null`.
5
6	`@see {@link IsNull}`
7
8	`@example`
9	```
10	`import type {IfNull} from 'type-fest';`
11
12	`type ShouldBeTrue = IfNull<null>;`
13	`//=> true`
14
15	`type ShouldBeBar = IfNull<'not null', 'foo', 'bar'>;`
16	`//=> 'bar'`
17	```
18
19	`@category Type Guard`
20	`@category Utilities`
21	`*/`
22	`export type IfNull<T, TypeIfNull = true, TypeIfNotNull = false> = (`
23	`IsNull<T> extends true ? TypeIfNull : TypeIfNotNull`
24	`);`