PSA: New Promise-based IndexedDB.jsm module

Kris Maglione kmaglione at
Sun Mar 26 19:17:41 UTC 2017

On Sun, Mar 26, 2017 at 11:03:38AM +0200, Dão Gottwald wrote:
>For those who are curious like me, it looks like extension meta data is our
>first and so far only consumer of this:
>Kris, what lead you to wanting to use IndexedDB here? What are the
>tradeoffs compared to mozstorage or plain JSON (see sessionstore)?

Two main reasons:

1) The normalized data we store needs to contain non-JSON types 
like Maps. IndexedDB supports this.

2) Parsing JSON was one of the most expensive things we were 
doing on the main thread during startup. Deserializing 
structured clone data from IndexedDB has proven to be much 

More information about the firefox-dev mailing list