What are free variables?

Question

Javascript closure definition says :

A \"closure\" is an expression (typically a function) that can have free variables together with an environment

Answer 1

As an example:

var myModule = (function (){
   var moduleVar; // closure variable

   return function(){
     // actual function
   }
})();

the variable defined there is a closure variable. it can be used all over the closure itself but is not part of a global namespace.