Invoking update function when changing document in Fauxton

Hello,
I would like to add a simple functionality using update function in design document. I would like it to be invoked when a document is changed/created in Fauxton.
Normally, one has to call the update function explicitly, but this (I believe) not possible with Fauxton.

Is there any way to achieve behaviour described above? Maybe it's possible to set an update function as default, so it doesn't require explicit call?

Thanks!

The issue names Fauxton and CouchDB update functions but no files, tests, or entry points. Start by reviewing Fauxton's document editing flow and the documented update-function behavior; done would require an agreed design and verification that changing or creating a document invokes the intended function.

Written by the indexing model from the issue text.