The efficiency and options of my PNG sequence JS class
I would suggest a few minor changes:


Use setTimeout instead of setInterval to ensure that callbacks don't stack up if they can't be serviced on time.  This implies re-invoking this.interGo at the end of the callback to re-trigger the timer.
Only declare and use self in the functions that need it, to avoid traversing the scope chain unnecessarily.
Remove over-reliance on the Number constructor.