how to dynamically increment a variable field mongoDB

I have this mongo collection opponents:

{username:foo, foo:{}} //the foo embedded document is to store foo's opponents'names and  round numbers
{username:foo1,foo1:{}}//the foo1 embedded document is to store foo1's opponents'names and  round numbers
{username:foo2,foo2:{}}//the foo1 embedded document is to store foo2's opponents'names and  round numbers

And this tableobject in the node.js server side:

table = {players:[name:foo,rounds:3],[name:foo1,rounds:3],[name:foo2,rounds:3]} //this is all the players' name in a table with their rounds number

For each player in a table, I want to append their opponents' names and rounds times to their embedded document in the opponent collection accordingly(of course no need to append themselves). So the desired results is:

{username:foo, foo:{foo1:3,foo2:3}}
{username:foo1,foo1:{foo:3,foo2:3}}
{username:foo2,foo2:{foo:3,foo1:3}}

This is my code:

First I have a custom function getArr(player) to return each player an array of their opponents names. so getArr(table.players[0]) would return [foo1,foo2]

// loop through the players
for (var i = 0 ;i < table.players.length; i++){
   // loop through the getArr() array which is one number shorter than players
  for (var j = 0; j< table.players.length -1; j++){
   console.log(i) // print "i" 6 times?
   db.opponents.update({username:table.players[i].name},{$inc:{[[table.players[i].name][getArr(table.players[i])[j]]]:table.players[i].rounds}})
   }
 }

Issue one: [[table.players[i].name][getArr(table.players[i])[j]]]is not defined.

Issue two: this nested loop seems to complicate the work as it executesconsole.log(i) more times than it should.

via Wei Zheng