Hi James
About "mode" option: Yes, I see it works for first mode number.
I'll find a better way to solve this later.
Actually, I decided that "mode" option would return the first input number if there is no mode number.
(having no output causes "Display" node to error)
But if you don't need that, it is as easy as changing this line:

var item = array[0];

to this:

var item ;

I think changing "idxSelect" node to have an inverse mode is possible, But I need to study the code more.

Although I was working on a new node to kinda solve this problem. I called it "FilterArray" node!
I was going to post it, But you were quicker. :)
It searches through an array of numbers and outputs filtered/unfiltered numbers and their indices.

"FilterArray" node

I am VERY happy with the direction this thread took.

I am learning tons.

Thanks to all of you that are posting Node information.

Tom