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

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419 BTypeScriptView Raw

1/**
2Returns a boolean for whether the given type is `null`.
3
4@example
5```
6import type {IsNull} from 'type-fest';
7
8type NonNullFallback<T, Fallback> = IsNull<T> extends true ? Fallback : T;
9
10type Example1 = NonNullFallback<null, string>;
11//=> string
12
13type Example2 = NonNullFallback<number, string>;
14//=? number
15```
16
17@category Type Guard
18@category Utilities
19*/
20export type IsNull<T> = [T] extends [null] ? true : false;

1	`/**`
2	Returns a boolean for whether the given type is `null`.
3
4	`@example`
5	```
6	`import type {IsNull} from 'type-fest';`
7
8	`type NonNullFallback<T, Fallback> = IsNull<T> extends true ? Fallback : T;`
9
10	`type Example1 = NonNullFallback<null, string>;`
11	`//=> string`
12
13	`type Example2 = NonNullFallback<number, string>;`
14	`//=? number`
15	```
16
17	`@category Type Guard`
18	`@category Utilities`
19	`*/`
20	`export type IsNull<T> = [T] extends [null] ? true : false;`