const set1 = new Set();
set1.add({x: 10, y: 20}).add({x: 20, y: 30});

// Delete any point with `x > 10`.
set1.forEach(function(point){
  if (point.x > 10) {
    set1.delete(point);
  }
});

console.log(set1.size);
// expected output: 1