Restore the Last Reading Position

Task

Load the saved CFI before displaying the EPUB.

Fetch the user’s progress for the Book, then:

const progress = await fetchProgress(bookId);

if (progress?.cfi) {
  await rendition.display(progress.cfi);
} else {
  await rendition.display();
}

Make sure book.locations.generate(...) has completed before percentage-based calculations are used.

If a stored CFI is invalid for the current EPUB, fall back to the default location instead of leaving the Reader blank.

Test

1. Open a book.
2. Read several pages.
3. Leave the Reader.
4. Reopen the same book.

The Reader should return to approximately the same position.

Checkpoint

Reopening a Book restores the user’s last persisted EPUB position.