I'm writing code against indexedDB (which doesn't use promises), but I want to expose promises to my callers. So I'm wrapping my indexedDB usage in Promises.
Also some of indexedDB doesn't seem like it would fit with promises, since some operations have 3 or more callbacks (onsuccess, onerror, onupgradeneeded).
There are a number of IndexedDb libraries that uses promises. However, there is or was a problem with how IndexedDb is specified to work that is not really compatible with promises. I'm not sure if they have fixed this yet.
https://github.com/promises-aplus/promises-spec/issues/45#is...
I can see the benefits of the indexedDb behavior: an open transaction is an exclusive resource, so leaving one dangling locks out other transactions. The auto-commit behavior means it's a lot harder to accidentally leave a transaction dangling. But it is unfortunate that this makes it not play nicely with promises.
Also some of indexedDB doesn't seem like it would fit with promises, since some operations have 3 or more callbacks (onsuccess, onerror, onupgradeneeded).