callbackFunction — if desired, return
a number from callback to update the duration of the trigger animation
step. Doing so will make any previous calculations of remaining animation
time incorrect. Make sure to initialize this step with a non-zero duration
for this to work.
TriggernAnimationStep options object
callbackFunction— if desired, return a number fromcallbackto update the duration of the trigger animation step. Doing so will make any previous calculations of remaining animation time incorrect. Make sure to initialize this step with a non-zero duration for this to work.payloadany— payload to pass to callback (null)