voluptasmollitia/docs-exp/performance.initializeperformance.md

Monorepo for the Firebase JavaScript SDK

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[Home](./index.md) &gt; [@firebase/performance](./performance.md) &gt; [initializePerformance](./performance.initializeperformance.md)

## initializePerformance() function

Returns a FirebasePerformance instance for the given app. Can only be called once.

<b>Signature:</b>

```typescript
export declare function initializePerformance(app: FirebaseApp, settings?: PerformanceSettings): FirebasePerformance;
```

## Parameters

|  Parameter | Type | Description |
|  --- | --- | --- |
|  app | [FirebaseApp](./app.firebaseapp.md) | The <code>FirebaseApp</code> to use. |
|  settings | [PerformanceSettings](./performance.performancesettings.md) | Optional settings for the <code>FirebasePerformance</code> instance. |

<b>Returns:</b>

[FirebasePerformance](./performance.firebaseperformance.md)