Nested iframe communication using contentWindow and window parent

In this video I have explained a very simple way of communicating two iframes using contentWindow and window.parent .

[@khushbooraj779]

Very informative

[@andrewpravin9664]

Thank you
this is very much useful.can you please attach the code

[@codewithshekhar94]

Sure pravin give me some time I will add the code

[@IzludeTingel]

I'm stuck... here's my setup (adobe animate canvas):
main clip, frame 2 spawns 0 with mkdiv
0 frame 1 spawns 1 with mkdiv
1 has a button and when I press it, I want it to move the timeline of 0 forward by 1. same website, same domain. how do I do this? (looking for a ready to copy/paste/use code, others have tried suggesting postMessage(); but I can't seem to get it to work...
also in the mix, i seem to be required to post window.parent most of the time, see if that info is useful if you have an answer :)