Recently I noticed that there is not a difference between these two snippets.

function step() {
  if (!this.counter) this.counter = 0;
  return this.counter++;
}

console.log(step()); // -> 0
console.log(step()); // -> 1
console.log(step()); // -> 2

function step() {
  if (!this.counter) this.counter = 0;
  return this.counter++;
}

step.counter = 10;

console.log(step()); // -> 0
console.log(step()); // -> 1
console.log(step()); // -> 2

Why does setting a function property not affect it's this?