As per the sample we can search for nodes and get back the results in the form of an iterator. As a result it is possible to navigate to the next item in the results but do we have anything which allows to go to the previous element in the search results once iterated to the next one?
You will need to copy the collection into a List or Array and keep an index of where the user “is”.
var arr = new go.List(results).toArray();