[READ-ONLY] If true, the timeline's timing mode is frames-based instead of seconds. This can only be set to true by passing useFrames:true in the vars parameter of the constructor, or by nesting this timeline in another whose timing mode is frames-based. An animation's timing mode is always determined by its parent timeline).
GreenSock Docs (HTML5/JS)
TimelineLite
.useFrames()
.useFrames( ) : Boolean
[READ-ONLY] If true, the timeline's timing mode is frames-based instead of seconds.
