---
lang: en
title: 'API docs: express.middlewarebindingoptions.downstreamgroups'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/express
permalink: /doc/en/lb4/apidocs.express.middlewarebindingoptions.downstreamgroups.html
---

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[Home](./index.md) &gt; [@loopback/express](./express.md) &gt; [MiddlewareBindingOptions](./express.middlewarebindingoptions.md) &gt; [downstreamGroups](./express.middlewarebindingoptions.downstreamgroups.md)

## MiddlewareBindingOptions.downstreamGroups property

An array of group names for downstream middleware in the cascading order.

For example, the `sendResponse` depends on `invokeMethod` for response processing. The `downstreamGroups` for `sendResponse` should be `['invokeMethod']`<!-- -->. The order of groups in the array does not matter.

**Signature:**

```typescript
downstreamGroups?: string | string[];
```