[Home](./index.md) > [@firebase/storage](./storage.md) > [StorageObserver](./storage.storageobserver.md) ## StorageObserver interface A stream observer for Firebase Storage. Signature: ```typescript export interface StorageObserver ``` ## Properties | Property | Type | Description | | --- | --- | --- | | [complete?](./storage.storageobserver.complete.md) | CompleteFn \| null | (Optional) | | [error?](./storage.storageobserver.error.md) | (error: [FirebaseStorageError](./storage.firebasestorageerror.md)) => void \| null | (Optional) | | [next?](./storage.storageobserver.next.md) | NextFn<T> \| null | (Optional) |