node.js - MongoDB how to find nearest neighbors -

i trying create simple leaderboard using mongo. have api build node.js , express.

for have json sorted user points looks this:

[     {     "_id": "58e543758222ff220d0af481",     "id": 5,     "__v": 0,     "name": "frank",     "points": 653     },     {     "_id": "58e543758222ff220d0af479",     "id": 1,     "__v": 0,     "name": "bob",     "points": 321     },     {     "_id": "58e543758222ff220d0af47b",     "id": 2,     "__v": 0,     "name": "john",     "points": 123     },     {     "_id": "58e543758222ff220d0af47d",     "id": 3,     "__v": 0,     "name": "bravo",     "points": 34     },     {     "_id": "58e543758222ff220d0af47f",     "id": 4,     "__v": 0,     "name": "bill",     "points": 12     } ] 

i have request looks this:

user.find().sort({ points: '-1' }).exec(function(err, users) {     if (err)         res.send(err);      res.json(users); }); 

and request find specified id.

user.findone({id: req.params.id}, function(err, user) {     if (err)         res.send(err);     res.json(user); }); 

i send id of user , info him. don't know how find nearest neighbor of specified id. example find user id: 3 how show 1 user before him , 1 after him using points.

thank you

another way query users , filter out using resultset.

user.find().sort({ points: '-1' }).exec(function (err, users) {     if (err)         // idea add return stop code going further         return res.send(err);      var nbd = [];     (var = 0; < users.length; i++) {         // find user given id         if (users[i].id == req.params.id) {             // add user before him             if (i-1 >= 0) {                 nbd.push(users[i-1]);             }             // add user             nbd.push(users[i]);             // add user after him             if (i+1 < users.length) {                 nbd.push(users[i+1]);             }             // no need search further             break;         }     }      res.json(nbd); });