When actually is a closure created?

Question

Is it true that a closure is created in the following cases for foo, but not for bar?

Case 1:

Answer 1

Actually, after several more years of JavaScript use and fairly thorough studies of it, I now have a better answer:

Whenever a function comes into existence, then a closure is created.

Because a function is just an object, we can more precisely say, whenever a Function object is instantiated (the function instance comes into existence), a closure is created.

So,

function foo() { }

When the JS completes running the above line, there is a closure already, or

var fn = function() { };

Or

return function() { return 1; };

Why? Because a closure is just a function with a scope chain, so in every situation above, a function existed (it came into existence. You can call it (invoke it)). It also had a scope. So in my original question (I was the OP), every Case 1 to 4, there was a closure created, in every single case.

Case 4 is an interesting case. After that code is run, there is a closure due to foo() coming into existence, but bar() doesn't exist yet (without the calling of foo()), so there was one closure created, not two.