Getting and Removing Button Classes

I have a project that contains a segmented button. Upon initialization, the first button gets assigned a class of 'lastPressed'. Each time one of the segmented buttons are toggled, I want to:

1. Remove the 'lastPressed class from any of the buttons


2. Add the 'lastPressed' to the pressed button

Number 1 (above) is where I am having the problem. For some reason I can't seem to be able to get the element with the 'lastPressed' class in order to remove the class. Any help?

Additionally, I want to be able to get the button that contains the 'lastPressed' class and determine its order in the array of segmentedbutton innerItems. How might I be able to accomplish this?

Here's a Fiddle for reference:

Getting and Removing Button Classes