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defu

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Recursively assign default properties. Lightweight and Fast!

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declare type Input = Record<string | number | symbol, any>; declare type Merger = <T extends Input, K extends keyof T>(obj: T, key: keyof T, value: T[K], namespace: string) => any; declare type MergeObjects<Destination extends Input, Defaults extends Input> = Destination extends Defaults ? Destination : Omit<Destination, keyof Destination & keyof Defaults> & Omit<Defaults, keyof Destination & keyof Defaults> & { -readonly [Key in keyof Destination & keyof Defaults]: Destination[Key] extends null ? Defaults[Key] extends null ? null : Defaults[Key] : Defaults[Key] extends null ? Destination[Key] : Merge<Destination[Key], Defaults[Key]>; }; declare type DefuFn = <Source extends Input, Defaults extends Input>(source: Source, ...defaults: Defaults[]) => MergeObjects<Source, Defaults>; interface Defu { <Source extends Input, Defaults extends Input>(source: Source, ...defaults: Defaults[]): MergeObjects<Source, Defaults>; fn: DefuFn; arrayFn: DefuFn; extend(merger?: Merger): DefuFn; } declare type MergeArrays<Destination, Source> = Destination extends Array<infer DestinationType> ? Source extends Array<infer SourceType> ? Array<DestinationType | SourceType> : Source | Array<DestinationType> : Source | Destination; declare type Merge<Destination extends Input, Defaults extends Input> = Destination extends null ? Defaults extends null ? null : Defaults : Defaults extends null ? Destination : Destination extends Array<any> ? Defaults extends Array<any> ? MergeArrays<Destination, Defaults> : Destination | Defaults : Destination extends Function ? Destination | Defaults : Destination extends RegExp ? Destination | Defaults : Destination extends Promise<any> ? Destination | Defaults : Defaults extends Function ? Destination | Defaults : Defaults extends RegExp ? Destination | Defaults : Defaults extends Promise<any> ? Destination | Defaults : Destination extends Input ? Defaults extends Input ? MergeObjects<Destination, Defaults> : Destination | Defaults : Destination | Defaults; declare const defu: Defu; export default defu;