objectPath.js

var getObj = {
  a: {
    foo: 1,
    bar: 2
  }
};

var objectPath = function(obj, path, value, options){
  path = typeof path == 'string' ? path.split('.') : path;
  var key = path.shift()
    , result = {};

  if(key && path.length){
    if(!obj[key]){
      if(value)
        obj[key] = {};
      else
        return undefined;
    }

    if(!value)
      return objectPath(obj[key], path, value, options);
    else
      obj[key] = objectPath(obj[key], path, value, options);
  } else {

    if(value){
      typeof obj == 'object' || (obj = {});
      result[key] = obj[key] = value;

      return obj;
    } else {
      if(options && options.unset){
        delete obj[key];
      } else {
        return obj[key];
      }
    }
  }
}

var has = function(obj, path){
  path = typeof path == 'string' ? path.split('.') : path;
  if(!obj || 'object' !== typeof obj)
    return false;

  var currentKey = path.shift();

  if(currentKey){
    if(!path.length){
      return obj.hasOwnProperty(currentKey);
    }
    return has(obj[currentKey], path);
  }
}

//objectPath(getObj, 'a', 55);
console.log('Original object', getObj);
objectPath(getObj, 'a.b', 66);
console.log('Object after set', getObj);
console.log('get a.b>', objectPath(getObj, 'a.b'));
//unset
objectPath(getObj, 'a.b', undefined, { unset: 1 });
console.log('unset a.b>', getObj);
//has
console.log('getObj has a?>', has(getObj, 'a'));
console.log('getObj has a.foo?>', has(getObj, 'a.foo'));
console.log('getObj has a.foo.faz?>', has(getObj, 'a.foo.faz'));
console.log('getObj has a.baz?>', has(getObj, 'a.baz'));