---
lang: en
title: 'API docs: repository-json-schema.optional'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/strongloop/loopback-next/tree/master/packages/repository-json-schema
permalink: /doc/en/lb4/apidocs.repository-json-schema.optional.html
---

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[Home](./index.md) &gt; [@loopback/repository-json-schema](./repository-json-schema.md) &gt; [Optional](./repository-json-schema.optional.md)

## Optional type

Optional: From `T` make a set of properties by key `K` become optional

<b>Signature:</b>

```typescript
export declare type Optional<T extends object, K extends keyof T = keyof T> = Omit<T, K> & Partial<Pick<T, K>>;
```

## Example


```ts
type Props = {
  name: string;
  age: number;
  visible: boolean;
};

// Expect: { name?: string; age?: number; visible?: boolean; }
type Props = Optional<Props>;

// Expect: { name: string; age?: number; visible?: boolean; }
type Props = Optional<Props, 'age' | 'visible'>;

```