CheckServer/vendors/jquery.easy-pie-chart/docs/callbacks.md

All callbacks will only be called if animate is not false.

Callback(params, ...)	Description
onStart(from, to)	Is called at the start of any animation.
onStep(from, to, currentValue)	Is called during animations providing the current value (the method is scoped to the context of th eplugin, so you can access the DOM element via this.el).
onStop(from, to)	Is called at the end of any animation.