Multiple ring donut chart using D3js v4
help you fix your problem I rewrote a bit your code. Check, now it works.
Pay attention that I extend data object with property parentIndex when I
store the index of the current data item. In d3 version 3 you can get the
index of parent data-item as
Date : November 19 2020, 03:01 PM , By : Christer Sonesson