Call of object.method from event gets empty object

yes, it's because this is set based on how the function is called.

O.M(); // this==O

var A = {};
A.M = O.M;
A.M(); // this==A

var f = O.M();
f(); // this==undefined <- what is happening with setInterval

You can always just do:

setInterval(() => O.M(), 1000)