Kata from: http://www.codewars.com/kata/514b6c44a337752e67000077

Name Your Namespace

Finish the namespace function so that it sets or gets the value at the path
specified. The first argument should be the root object that the path belongs to.
The 2nd argument is the path itself and the 3rd optional argument is the value 
to set at the path.

If a value is provided then the path will be set to that value. Any objects not 
present within the path will be created automatically in order for the path to 
be successfully set.

/* CODE
 *    stuff = {}
 *    namespace(stuff, 'moreStuff.name', 'the stuff')
 *    
 *    results in {moreStuff: {name: 'the stuff'}}
 */

If no value is provided the the function will return the value at the path given. 
If the path is not valid/present then undefined will be returned.

/* CODE
 *      namespace(stuff, 'moreStuff.name') # returns 'the stuff'
 *      namesace(stuff, 'otherStuff.id') # returns undefined
 */

nameyournamespace.js

function namespace(root, path, value){
    var parts = path.split(".");
    
    function setValue(objScroller, parts, value) {
        var i;
        
        for (i = 0; i < parts.length - 1 ; i++) {
            if (!objScroller.hasOwnProperty(parts[i])) {
                objScroller[parts[i]] = {};
            }
          
            objScroller = objScroller[parts[i]];
        }
        
        objScroller[parts.pop()] = value;
     }
     
    function getValue(objScroller,parts) {
        var i;
       
        for (i = 0; i < parts.length - 1 ; i++) {
              if (!objScroller.hasOwnProperty(parts[i])) {
                  return undefined;
              }
          
              objScroller = objScroller[parts[i]];
        }
      
        return objScroller[parts.pop()];
    }
     
    return (value) ? setValue(root,parts,value) : getValue(root,parts);

}

Coincidentally, I was just reading Nickolas Zackas' "Maintanable Javascript" where he was talking about the namespace function for your One Global Object. That served as inspiration for most of this kata.