Just to let you know if you get excited about it:
https://pivottable.js.org/ works superbly well with SF, it is quite easy to get a basic pivot table up and running.
The painful part starts - and that is purely SF, nothing to do with the excellent JS module - when you try to generalise it to be able to define and run any query to feed the pivot.
1)    If you generalise the query to get an SObject list, you have methods to get the field names and labels but it gets a tad more complicated if you want to include reference fields (e.g.: Account.Name from Opportunity or even Account.Parent.Name from Opportunity)
2)    You can use AggregateResult (much easier to manage labels as you can alias fields here and JSON serialise works very well)
BUT it is limited to 2000 lines unless you implement an AggregateResult Iterator to which I’m trying to wrap my head around.
3)    You can very easily hit SF governor limits (both the heap- and the CPU limits) while processing query result lines so you’ll need to make it as efficient as possible. I reduced my query to a mere ~ 20 000 lines but still hitting limits.
When I got the first basic version working, I wanted to share but I’m currently struggling with the limitations above and see no point in that until these are resolved.
Best of luck to anyone going for it.