voluptasmollitia/docs-exp/app.onlog.md

Monorepo for the Firebase JavaScript SDK

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[Home](./index.md) &gt; [@firebase/app](./app.md) &gt; [onLog](./app.onlog.md)

## onLog() function

Sets log handler for all Firebase SDKs.

<b>Signature:</b>

```typescript
export declare function onLog(logCallback: LogCallback | null, options?: LogOptions): void;
```

## Parameters

|  Parameter | Type | Description |
|  --- | --- | --- |
|  logCallback | LogCallback \| null | An optional custom log handler that executes user code whenever the Firebase SDK makes a logging call. |
|  options | LogOptions |  |

<b>Returns:</b>

void