create.js

(function() { /* creates a new scope */
     var created = {}; // all objects that have been created.

     function create(name, value) {
         /* this is within the main function's scope, so we have access to all
            variables defined in it from here */
         var obj = {};
         if (!created[name]) {
             obj.data = value;
             created[name] = obj;
         }
     }

     create('foo', 'bar'); // creates `foo`
     create('bar', 'baz'); // creates `bar`
     create('foo', 'baz'); // doesn't create `foo` because it has already been
                           // created.

     console.log(created);
}());