manast

And just to illustrate with one use case where this would be important. Let's say that you have a playlist with songs (or videos), and you want to control the playlist with one parent timeline so that you can have one slider used to move from the different songs, as if the songs where actually stitched together as one single piece. In this case, you would like to have one child timeline for every song, and then add every child timeline to the parent timeline which would then be the UI-facing timeline to control the playlist.

@GreenSock If I am not mistaken, this technique of overriding the play/pause/seek methods would not work if the timeline is a child timeline right? As if the parent timeline will not call these child timeline methods when playing, pausing, or seeking. Is there any obvious way to make this case work as well?

@GreenSock thank you for this comprehensive answer, it is really helpful indeed ?.

@ZachSaucier There are a couple of problems with this approach. The first one is that maybe the video is associated with a child's timeline, so when doing a play or pause on the parent timeline we cannot just play or pause the video as the child's timeline may start later in time. The second issue is that the approach suggested assumes that we have access to the video in the same place as the tween, that will not always be the case as maybe you are working with a timeline that is created at some top-level whereas the video is created deep inside a web component or something like that. What would really be useful is if there were callbacks that fired every time a timeline started playing (note it is not the same as onStart as we could start playing from the middle of the timeline), as well as callbacks for seek and stop. With a set of callbacks like this, it would be super easy to integrate with stuff like the video tag or any other external animation system.