Mongoose find array with $in
If teamIds is already an array, then you shouldn't wrap it in another array:
Team.find({ '_id': { $in: teamIds }}, function(err, teamData) { console.log("teams name " + teamData);});Or, if teamIds is a string of comma-separated id values, you need to convert it into an array of values using split:
Team.find({ '_id': { $in: teamIds.split(',') }}, function(err, teamData) { console.log("teams name " + teamData);});