Can't run a container cleanup before the cache snapshot

[fredck]

When integrating a component within a pjax enabled website, I have a strong need of cleaning up a few elements from the dom before pjax saves the current container snapshot.

At first, I though that the pjax:beforeReplace event was ideal for it - after all, "replace" can be understood like "remove the current one (take the snapshot) and inject the new one". It was too late.

Then, I thought about the pjax:start event... but for that, I went to check the source code:
https://github.com/defunkt/jquery-pjax/blob/153262eda33e31119eabb97cd5f14365580a3b35/jquery.pjax.js#L370-L371

Conclusion:

• There is zero difference between pjax:start and pjax:send: 
  • it doesn't seem to be useful.
  • they happen way after things "started" and the xhr was "sent".
• All these events happen after the snapshot has been already taken, a few lines before.

Q1 (proposal): shouldn't pjax:start happen somewhere earlier in the code?

Q2 (help!): how to safely tweak the dom before the snapshot is taken into the cache?