Frontend & browser·Storage and platform APIs
you needed to keep megabytes of structured data on the device, so key-value strings were not enough.
IndexedDB
Also calledindexed database, IDB
An asynchronous, transactional, indexed object store with a much larger quota than web storage and support for structured values including blobs. It is the only real option for offline data and large client-side caches. Its native API is famously unpleasant, which is why nearly everyone uses a thin wrapper over it.