Returns the begin time, in seconds, for this animation element's current interval, if it exists, regardless of whether the interval has begun yet. If there is no current interval, then a DOMException with code INVALID_STATE_ERR is thrown.
Returns the current time in seconds relative to time zero for the given time container.
Returns the number of seconds for the simple duration for this animation. If the simple duration is undefined (e.g., the end time is indefinite), then a DOMException with code NOT_SUPPORTED_ERR is raised.