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conditional-pick.d.ts
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48 lines (37 loc) · 1.14 KB
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import type {ConditionalKeys} from './conditional-keys.d.ts';
import type {IsNever} from './is-never.d.ts';
/**
Pick keys from the shape that matches the given `Condition`.
This is useful when you want to create a new type from a specific subset of an existing type. For example, you might want to pick all the primitive properties from a class and form a new automatically derived type.
@example
```
import type {Primitive, ConditionalPick} from 'type-fest';
class Awesome {
constructor(public name: string, public successes: number, public failures: bigint) {}
run() {
// do something
}
}
type PickPrimitivesFromAwesome = ConditionalPick<Awesome, Primitive>;
//=> {name: string; successes: number; failures: bigint}
```
@example
```
import type {ConditionalPick} from 'type-fest';
type Example = {
a: string;
b: string | number;
c: () => void;
d: {};
};
type StringKeysOnly = ConditionalPick<Example, string>;
//=> {a: string}
```
@category Object
*/
export type ConditionalPick<Base, Condition> = ConditionalKeys<Base, Condition> extends infer Keys
? IsNever<Keys> extends true
? never
: Pick<Base, Keys & keyof Base>
: never;
export {};