---
title: Avoid the declaration of empty interfaces
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Datadog Security > Code Security > Static Code Analysis (SAST) > SAST
  Rules > Avoid the declaration of empty interfaces
---

> For the complete documentation index, see [llms.txt](https://docs.datadoghq.com/llms.txt).

# Avoid the declaration of empty interfaces

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## Metadata{% #metadata %}

**ID:** `typescript-code-style/no-empty-interface`

**Language:** TypeScript

**Severity:** Notice

**Category:** Best Practices

## Description{% #description %}

Do not use empty interfaces.

## Non-Compliant Code Examples{% #non-compliant-code-examples %}

```typescript
interface Foo {}
interface Foo extends {}
interface Bar extends Foo {}
interface Foo extends Array<number> {}
interface Foo extends Array<number | {}> {}
interface Foo extends Array<Bar> {}
interface Foo extends R {}
interface Foo<T> extends Bar<T> {}
declare module FooBar { type Baz = typeof baz; export interface Bar extends Baz {} }
interface Foo {

}
```

## Compliant Code Examples{% #compliant-code-examples %}

```typescript
interface Foo { name: string; }
interface Foo { name: string; }
interface Bar { age: number; }

// valid because extending multiple interfaces can be used instead of a union type
interface Baz extends Foo, Bar {}
interface Foo { name: string; }
interface Foo { props: string; }
class Bar {}
```
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