Suggestion on how to code the Conway's Game of Life

That looks great! The rescheduling would be good... I guess just:

y=0;
function next() {
    for (let x = 1; x<17; ++x){
       ...
        }
    }
   y++;
   if (y>=17) {
      flip();
     // restart
      y=0;
      // flip generations
      var t = genA;
      genA = genB;
      genA = t;
   }
}

You could then just use setInterval on next with a ~50ms interval?