[Home](./index.md) > [@firebase/firestore](./firestore.md) > [/](./firestore_.md) > [LoadBundleTask](./firestore_.loadbundletask.md) > [onProgress](./firestore_.loadbundletask.onprogress.md) ## LoadBundleTask.onProgress() method Registers functions to listen to bundle loading progress events. Signature: ```typescript onProgress(next?: (progress: LoadBundleTaskProgress) => unknown, error?: (err: Error) => unknown, complete?: () => void): void; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | next | (progress: [LoadBundleTaskProgress](./firestore_.loadbundletaskprogress.md)) => unknown | Called when there is a progress update from bundle loading. Typically next calls occur each time a Firestore document is loaded from the bundle. | | error | (err: Error) => unknown | Called when an error occurs during bundle loading. The task aborts after reporting the error, and there should be no more updates after this. | | complete | () => void | Called when the loading task is complete. | Returns: void