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index.d.ts
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index.d.ts
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/**
Deeply merges the given options with the specified defaults.
@param options - The user-provided options. If the value is not a plain object, a new plain object will be used instead.
@param defaultOptions - The default options to use when a value is not provided in the `options` object.
@returns A new object containing the merged options.
@example
```
import defaults from 'defaults';
const calculate = options => {
options = defaults(options, {
timeout: {
before: 100,
after: 100
}
});
console.log(options);
//=> {timeout: {before: 200, after: 100}}
// …
}
// …
calculate({timeout: {before: 200}});
```
*/
export default function defaults<T extends Record<string, unknown>, U extends Record<string, unknown> | undefined = undefined>(
options: T,
defaultOptions: U
): U extends undefined ? T : DeepMerge<U, T>;
type DeepMerge<T, U> =
T extends Record<string, unknown> ?
U extends Record<string, unknown> ?
{[K in keyof T | keyof U]: K extends keyof T ? K extends keyof U ? DeepMerge<T[K], U[K]> : T[K] : K extends keyof U ? U[K] : never}
: T
: U extends undefined ?
T extends undefined ?
U
: T
: U;