Using JavaScript to get the current slide number

I know this is way out there, but I'm hoping someone knows enough about Storyline's JS to help.

Like many others, I'd like to get the current slide number within each slide so I can use it in a custom JavaScript trigger. I'm using Storyline360, so I know some previous ways of getting this are no longer possible. I'll need to implement this on at least 17 courses which have around 40 slides each, so I'd rather avoid setting up that many triggers to count the slides.

One helpful thing I've found is that each slide loads a JS file which executes the function "globalProvideData," and the second parameter in that is a JSON string which includes a property "lmsId" with the value "SlideX." Does anyone know if there's a function to access the data provided by that function? If I could get my hands on that JSON string I could figure out the rest.

As I said, it's a long shot, but I can't find anything else about getting the slide number without manually setting up triggers and variables in the project. If anyone has any advice or suggestions, I'd greatly appreciate it.

Thanks in advance!