ExpressJS is redirecting after POST - mongodb

Question

I have following problem. My server which is written in ExpressJs (used MongoDB as database) is redirecting my page after registration ( POST method ). Why?
Server.js
const express = require('express');
const bodyParser = require('body-parser');
const app = express();
const morgan = require('morgan');
app.use(morgan('dev'));
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
const port = process.env.PORT || 9090;
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/db');
const router = express.Router();
app.use(function(req, res, next) {
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
next();
});
router.get('/', function(req, res) {
res.json({
"get | post": "/users"
});
});
app.use('/api', router);
require('./routes/users')(app,router);
app.listen(port);
console.log('Started server on port ' + port);
users.js
const User = require('../models/user');
module.exports = function(app, router){
app.post('/api/users',function(req, res) {
var user = new User();
user.name = req.body.name;
user.surname = req.body.surname;
user.email = req.body.email;
user.age = req.body.age;
user.login = req.body.login;
user.password = req.body.password;
user.created_at = req.body.created_at;
user.update_at = req.body.update_at;
user.save(function(err) {
if (err)
res.send(err);
res.json({
name: user.name,
surname: user.surname,
email: user.email,
age: user.age,
login: user.login,
password: user.password,
update_at: user.update_at,
created_at: user.created_at
});
});
})
app.get('/api/users',function(req, res) {
User.find(function(err, users) {
if (err)
res.send(err);
res.json(users);
});
});
}
user.service.ts
import { Observable } from 'rxjs/Observable';
import { Http, RequestOptions, Headers } from '#angular/http';
import { Injectable } from '#angular/core';
import { db_url } from './../../../assets/db_url';
import { User } from './../../../assets/interfaces/db.interface';
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/toPromise';
#Injectable()
export class UserService {
constructor(private _http: Http) {}
registerUser(user_data: User): Observable<any>{
let headers = new Headers({ 'Content-Type': 'application/json' });
let options = new RequestOptions({ headers: headers });
let url = "http://localhost" + db_url + "/users";
return this._http.post( url, user_data , options )
.map(data => data.json())
.catch(err => err);
}
}

Answer 1

Try add return operator to same places
app.get('/api/users',function(req, res) {
User.find(function(err, users) {
if (err)
return res.send(err); <<<
res.json(users);
});
});