javascript - Nodejs mongodb fetching document size without actually fetching cursor -

my question is, how can cursor size (in kbs) without fetching ?

i've examined lot of question such here don't want fetch query result learn how kb it.

i want like:

var mongoclient = require('mongodb').mongoclient,   test = require('assert'); mongoclient.connect('mongodb://localhost:27017/test', function(err, db) {    var collection = db.collection('simple_query');    // insert bunch of documents testing   collection.insertmany([{a:1}, {a:2}, {a:3}], {w:1}, function(err, result) {     test.equal(null, err);      collection.find(/**some query*/).size(function(err, size) {       test.equal(null, err);       test.equal(32111351, size); // in bytes or kilobytes whatever       db.close();     });   }); }); 

something this?

var avgsize = db.collectionname.stats().avgobjsize;  // ...  collection.count(/* query */, function(err, count) {     var approximatesize = count*avgsize; // work simple database models } 

i know not perfect, best way found.