type-fest/source/asyncify.d.ts

A collection of essential TypeScript types

import type {SetReturnType} from './set-return-type.d.ts';

/**
Create an async version of the given function type, by boxing the return type in `Promise` while keeping the same parameter types.

Use-case: You have two functions, one synchronous and one asynchronous that do the same thing. Instead of having to duplicate the type definition, you can use `Asyncify` to reuse the synchronous type.

@example
```
import type {Asyncify} from 'type-fest';

// Synchronous function
type Config = {featureFlags: Record<string, boolean>};

declare function loadConfigSync(path: string): Config;

type LoadConfigAsync = Asyncify<typeof loadConfigSync>;
//=> (path: string) => Promise<Config>
```

@category Async
*/
export type Asyncify<Function_ extends (...arguments_: any[]) => any> = SetReturnType<Function_, Promise<Awaited<ReturnType<Function_>>>>;

export {};