Confirmation：which version support compound index for IndexedDB, V12+?
Try to create multi-keypath index. Which FF version can support it, V12?
Additional System Details
- User Agent: Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.22 (KHTML, like Gecko) Chrome/25.0.1364.152 Safari/537.22
Not something I understand, you may do better at a forum such as
They do deal with Firefox Web Development
Also you may find information or links in this article is useful (I note it mentions fx11)
Note also Firefox versions have both release notes and developer notes
The earliest supported version is currently ESR17