Not this

notThis.js

function foo(num) {
  console.log( "foo: " + num );
  this.count++;
}

foo.count = 0;

foo(1); // foo: 1
foo(5); // foo: 5
foo(10); // foo: 10

console.log('Wrong: ', foo.count ); // Wrong: 0
console.log('Right: ', count); // Right: NaN