callable object

function my_func() { console.log(1); }
// let my_func = {};

my_func.x = -1;
my_func.y = 100;

console.log(my_func.x); // -1

delete my_func.x;

for(let key in my_func) {
  console.log(key, my_func[key]);
}
// "y" 100

my_func(); // prints 1