Extract some chars from a variable

I have a variable with the value “_level0.store.1” … is there any function in flash with which i can just take the 15th character and remove everything that is before the “1” --> basically i’d like to use “1” to read that position from an array… therefore i want something that:

_root.nodeFrom = this --> returns “_level0.store.1”

I would get:
positioninArray = 1