[dumbmatter]

That's actually not true in Chrome https://bugs.chromium.org/p/chromium/issues/detail?id=457409 although it's not clear if that is a bug in Chrome or in other browsers. It would be nice to have more clarity on that, or an explicit promise API like https://github.com/inexorabletash/indexeddb-promises because until then it's really shitty to use - you have to constantly worry about cross-browser compatibility.