do i need to delete the reference before reassingning a value to the key?

gistfile1.txt

//all of this code is in a function.

var docs = Meals.aggregate(pipeline)
	var oldData = Cache.regulars.data
	var newData = {};
	docs.forEach(function(doc){
		var id = doc._id
		var raw = _.omit(doc,'_id');
		newData[id] = raw
		var oldDoc = oldData[id]
		if (oldDoc && (raw.score.total-oldDoc.score.total)){
			self.changed('regulars',id,{score:raw.score})
		} else {
			self.added('regulars',id,raw);
		}
	})
	delete Cache.regulars.data;
	Cache.regulars.data = newData;