Strongly-typed deep and recursive object merging with support for all value types.

## Install ```bash pnpm add object-deep-merge ``` ```bash yarn add object-deep-merge ``` ```bash npm install object-deep-merge ``` ## Basic Usage ```ts import { merge } from "object-deep-merge"; ``` ### Simply merge two objects, with no nested properties ```ts const merged = merge({ foo: false }, { bar: true }); console.log({ merged }); ```

Output

```json { "merged": { "foo": false, "bar": true } } ```

## Typed Usage ### `merge` Type Signature The `merge` function accepts two optional type generics. `TData` and `TResult`. ```ts function merge( source: TData, target: TData, ...targets: Array ): TResult; ``` > [!IMPORTANT] > The [`Merge`](https://github.com/sindresorhus/type-fest/blob/main/source/merge.d.ts) and [`MergeDeep`](https://github.com/sindresorhus/type-fest/blob/main/source/merge-deep.d.ts) types from [`type-fest`](https://github.com/sindresorhus/type-fest) are great additions to this library. It is not unreasonable to use those types for your merge typing needs. Without explicitly passing in types the function will infer the shape of the object(s) passed in. - Passing in `TData` will validate the shape of the objects passed in. - Passing in `TResult` will override the output type. While this should be used sparingly, it provides a convenient approach for correctly typing partial types into complete types. ### Simple Example w/o Generics ```ts type Data = { name: string; description: string; }; const base: Data = { name: "object-deep-merge", description: "merge objects" }; const overrides: Partial = { description: "merge objects, deeply" }; const merged = merge(base, overrides); // Type is inferred so the signature becomes: // function merge, Partial>(source: Partial, target: Partial, ...targets: Partial[]): Partial // TData = Partial // TResult = Data console.log({ merged }); ```

Output

```json { "merged": { "name": "object-deep-merge", "description": "merge objects, deeply" } } ```

### Simple Example w/ `TData` Generic > [!NOTE] > Passing in TData will validate the shape of the objects passed in. ```ts type Data = { name: string; description: string; }; const base: Data = { name: "object-deep-merge", description: "merge objects" }; const overrides: Partial = { description: "merge objects, deeply" }; const merged: Partial = merge>(base, overrides); // TData = Partial // TResult = Data console.log({ merged }); ```

Output

```json { "merged": { "name": "object-deep-merge", "description": "merge objects, deeply" } } ```

### Simple Example w/ `TData` and `TResult` Generics > [!NOTE] > Passing in `TResult` will override the output type. While this should be used sparingly, it provides a convenient approach for correctly typing partial types into complete types. ```ts type Data = { name: string; description: string; }; const base: Data = { name: "object-deep-merge", description: "merge objects" }; const overrides: Partial = { description: "merge objects, deeply" }; const merged: Data = merge, Data>(base, overrides); // TData = Partial // TResult = Data console.log({ merged }); ```

Output

```json { "merged": { "name": "object-deep-merge", "description": "merge objects, deeply" } } ```