The goal is to know if user actually shared some content and if he did to reward him. It can be either share or like button, doesn't matter.
I did find the edge.create
event in JS SDK but it's not good enough (as far as I tested), because the event is just after clicking like button, not when he actually posts the info on his wall or timeline.
I need to do it without asking for any permissions, if that's possible. Preferably using JS.
You can use the code here: redirect user after facebook share and publish
The share function
FB.ui({
method: 'feed',
...
has a callback which you can use to suit your needs