I am new to CouchDd so I may have missed something in documentation.

I want to create a map function that will drop on of the members of doc. Note: I do not want to actually change the stored document only the result returned. 

I have created this map.

```
function(doc) {
    for(i = 0; i < doc.Videos.length; i++)
    {
        delete doc.Videos[i].VideoFrames;
    }
    emit(doc.DeviceId, doc);
}

```

* doc.Videos is an array
* Each element of Videos has a memember VideoFrames.

I want to delete VideoFrames from the document returned by CouchDb.

When I run this map however VideoFrames are still in the returned document. I ran this map with sample data in JSFiddle and it works as I would expect, however, when in couchDB it is not.

A sample doc

```
{
   "_id": "2e06de647c59fc94524c2f90b7001157",
   "_rev": "1-cb05705a122918c2c53dfb1e01ebed02",
   "TimeStamp": 1397343510,
   "DeviceId": "74a5f7aa9d4dfd0d",
   "Videos": [
       {
           "TimeStamp": 1397343518798,
           "VideoFrames": [
               {
                   "TimeStamp": 1397343519515,
                   "JPEG_Base64Frame": "iVBORw0KGgoAAAANSUh...==\n"
               }
           ]
       }
   ],
   "GeoLocations": [
       {
           "TimeStamp": 1397343512,
           "Latitude": 41.5654724,
           "Longitude": -87.5268132
       }
   ]
}

```