Need index of {{rects}} for use in 'Custom' exporter

[jcbk101]

Hello, all. Is it possible for any one of you contributors who understand javascript to add an exportable variable that can be accessed inside of the 'custom' exporter (using mustache)?

I need a numerical index reference for each '{{rects}}' that is process, preferably starting at 1 and not zero. I was trying to do it myself but I have zero clue on how to even install / run the javascript code. Thanks for any help.