Library and collection methods

createOfflibrary(config) returns an Offlibrary; library.collection(name) returns a Collection. Every collection method waits for library.ready, so you can call them right away.

Offlibrary

Member	Description
ready: Promise<void>	Resolves once metadata is loaded and in-flight downloads are re-attached. Collection methods wait for it, so you rarely need to.
collection(name)	Returns the Collection. Throws unknown-collection for names not in the config.
collectionNames	Configured collection names.
on(type, listener)	Typed event listener. Returns an unsubscribe function. It’s also a regular EventTarget (addEventListener + CustomEvent.detail).
subscribe(listener)	Called on every change in any collection (change event). Returns an unsubscribe function.
storage.estimate()	{ usage, quota, available, supported }
storage.persist() / storage.persisted()	Wrappers around navigator.storage.persist() / persisted().
capabilities	{ serviceWorker, backgroundFetch, cacheStorage, indexedDB, storageEstimate, storagePersist, webLocks }
refresh()	Re-read metadata from IndexedDB. Runs automatically when the page becomes visible.
destroy()	Stop listening and pause running fetch downloads (they resume next time).

Collection

Method	Returns	Description
download(item)	Promise<OfflibraryItem>	Starts or continues a download and resolves once it has started. If the item is already stored with the same version, nothing is downloaded and it’s marked as recently used. Paused or failed items resume. Throws invalid-item, limit-exceeded or quota-exceeded before starting.
downloadAll(items)	Promise<PromiseSettledResult[]>	Calls download for each item.
done(id)	Promise<OfflibraryItem>	Resolves when the item completes; rejects with an OfflibraryError if it fails, pauses or is removed.
get(id) / peek(id)	OfflibraryItem | undefined	Async / sync state of one item.
list() / snapshot()	readonly OfflibraryItem[]	All items. snapshot() is sync and referentially stable until something in the collection changes.
has(id)	Promise<boolean>	true when the item is completed.
pause(id) / resume(id) / retry(id)	Promise<OfflibraryItem>	Pause is for the fetch transport only (Background Fetch has no pause and throws not-supported). Resume and retry continue paused or failed items.
cancel(id)	Promise<void>	Stops a download (including a Background Fetch) and removes the item.
delete(id)	Promise<boolean>	Removes the item and its stored files.
clear()	Promise<void>	Deletes every item in the collection.
match(id, url?) / blob(id, url?)	Response / Blob	The stored file (the first URL by default), for every storage kind. For storage: 'opfs' the Blob is the disk-backed OPFS File, not a copy in memory.
bytes(id, url?) / arrayBuffer(id, url?)	Uint8Array / ArrayBuffer	The stored file as bytes, the shape model runtimes take (ort.InferenceSession.create(await models.bytes('m'))). For items kept in memory it returns the buffer the download filled, without a copy.
usage()	{ count, bytes }	Completed items and their size.
sync(items, { prune })	(OfflibraryItem | undefined)[]	Updates titles and meta from your feed. With prune: true, deletes stored items no longer in it (pinned ones are kept).
touch(id)	Promise<OfflibraryItem>	Marks the item as recently used. The service worker does this when it serves a file.
subscribe(listener)	() => void	Change listener for this collection only. Pair it with snapshot().
name, config		Collection name and resolved policy.

Utilities

import { formatBytes, isBackgroundFetchSupported, OfflibraryError } from 'offlibrary';

formatBytes(1536);              // "1.5 KB"
isBackgroundFetchSupported();   // true when the browser exposes BackgroundFetchManager (Chromium)

Full signatures: API reference.