Client side (javascript/jQuery) file manipulation before/after upload/download

Question

I\'m just sounding things out about this having looked around for a while and drawn a blank. I\'d like to see if this is even possible as so far I can\'t see a way to do it.

Answer 1

The accepted answer is outdated here. It is possible to do this now using HTML5 File API and something like the CryptoJS library.