Stack/Unstack bar chart using Switch component

There is a ready nice example from oracle which shows how to stack/unstack a bar chart. It uses two independent buttons - one stacks a chart second one unstack it. Each one has a dynamic action with simple javascript code.

Now I would like to do the same but using one switch component. The point is I suppose I need to know the current stack setting for a chart. Someone can advice me how to do it ?

My current version of Apex is 21.8.

thanks in advance

K.