getting an empty array after I pushed some Json objs to it [duplicate]

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• Why is my variable unaltered after I modify it inside of a function? - Asynchronous code reference 3 answers

I could not figure out why my userProjects at the end prints an empty array.

var express = require('express');
var router = express.Router();
var idea = require("../models/idea_model");
/* GET home page. */
router.get('/', function (req, res, next) {
    //var sess = req.session;
    var userProjects = []
    try {
        if (sess.user.email) {
            console.log("see.user.projects: " + sess.user.projects);
            var proj_length = sess.user.projects.length;
            for (var i = 0; i < (proj_length); i++) {
                console.log("project name: " + typeof (sess.user.projects[i]) + " " + sess.user.projects[i]);
                idea.findOne({
                    title: sess.user.projects[i]
                }, function (err, docs) {
                    if (!err) {

                        if (!docs) {
                            console.log("error saving project to user");
                        } else {

                            userProjects.push(docs);

                        }
                    } else {
                        console.log(err);
                    }
                });
            }
            console.log("vvvvvvvvvvvvvvvvvvvvvvvvvvvv");
            console.log(userProjects); //Problem!!!!!!!!!!!!!!! empty array!!!
            res.render('user_dash', {
                user_proj: JSON.stringify(userProjects)
            });
            if (sess.cookie.maxAge <= 0) {
                sess = null;
            }
        }
    } catch (e) {
        res.render('login');
    }
});

module.exports = router;