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# provisionalDataSource

The provisional data source, or `nil` if either a load request is not in progress or a load request has completed.

```
var provisionalDataSource: WebDataSource! { get }
```

## Discussion

Use the [`load(_:)`](/documentation/WebKit/WebFrame/load(_:)-47p2s) method to initiate an asynchronous client request, which creates a provisional data source. The provisional data source transitions to a committed data source once any data is received.

---

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