Randomize uppercasing / lowercasing on all string characters

Kind of an odd request, I know. But I've been looking for a solution to this for quite a while now. This is the effect I'm looking for:

var myString = "Hello I am randomly capitalized"

Desired function result:

hElLO i aM rAnDOmlY caPiTAlizED

I imagine this is best done with javascript arrays in one way or another. Just looking for some creative ideas. Thank you!