I will shamelessly copy my SO question:
What I absolutely don’t get: after
checking a club
uncheck all players
check again the club, players property will have the players’ ids of the club. but it look like checked=(contains player.id players) does not react to it. Although adding some console.log to the helper shows that it will be computed:
There is a jsbin link too: http://jsbin.com/nanureqaba/16/edit?html,js,output.