Manipulate variable defined in closure

Question

Say I have a Javascript class defined and instantiated like this:

Demo = function() { 
  var abc = "foo";

  return {
    get test() { return abc; }
  }
}

obj = Demo();
obj.test  // evaluates to "foo"

Confronted only with this Demo instance obj, can I change the value of the variable abc belonging to this object, that was defined in the closure introduced by the constructur function?

Answer 1

var abc is NOT directly available outside the scope of Demo.

If you want to change it from outside that scope, you have to add a method to set it.

Demo = function() { 
  var abc = "foo";

  return {
    get test() { return abc; }
  }

  this.setTest(a) {abc = a;}
}

var obj = new Demo();
obj.setTest("fun");

See this previous discussion for examples of the types of accessors you could use.

Answer 2

No. This is one of the base uses for a closure - to define private, inaccessible variables. They can be retrieved, but unless there is a "setter" function, they cannot be modified.