elapsedTime property
num
elapsedTime
The amount of time the animation has been running, in seconds, when this event fired, excluding any time the animation was paused.
For an animationstart event, elapsedTime is 0.0 unless there was a negative value for animation-delay, in which case the event will be fired with elapsedTime containing (-1 * delay).
See developer.mozilla.org/en-US/docs/Web/API/AnimationEvent/elapsedTime
Implementation
external num get elapsedTime;