You are correct. In both of the top functions x in f refers to the parameter x.
There's some considerations with case 3.
In the third example if f isn't defined and you are returning x2 when calling the function it will be equal to whatever x originally was. When you do x = 5; you aren't changing x2. This is because when you assign x2 = x JavaScript makes a copy not a reference.
Unless the x parameter is passed an array or object x2 will be a copy and not a reference of x.
So if you do three(3) then x2 will always be 3 because you're never changing it.
