gistfile1.js

function eachUser(user) {
  // Suchabfrage starten
  graphabfrage.get(user.id, function(err, res) {
    if (err) console.log('FEHLER updatelocationids: '.JSON.stringify(err));
    dblocations.findOne({ id: user.id }, function (err, fbitem2){
      // bla bla ..
    })
  })
}

function foo(err, users) {
  users.forEach(eachUser)
}

function getLocations(req, res) {
  dblocations.find({ $or: [{"blacklist":"0"},{"whitelist":"1"}] } ).exec(foo)
}

app.get('/v1/getids', getLocations)