API Node.js + express, problem with request

I have problem i wrote simple API but when i want use method.I have information url: "http://localhost:4200/undefined/api/SaveUser" Can be a problems with routing? I dont know where is problem. I start node server and mongos. Did anyone have a similar problem?

code on my API

var express = require('express');
var path = require("path");
var bodyParser = require('body-parser');
var mongo = require('mongoose');
const port = process.env.PORT || 3000
var db = mongo.connect("mongodb://localhost:27017/crud", function(err, response){
    if(err) {console.log(err); }
    else { console.log("Connected to"+ db, " + ", response); }
});

var app = express();
app.use(bodyParser());
app.use(bodyParser.json({limit: '5mb'}));
app.use(bodyParser.urlencoded({extended:true}));

app.use(function (req, res, next) {
    res.setHeader('Access-Control-Allow-Origin', 'http://localhost:4200');
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');
    res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
    res.setHeader('Access-Control-Allow-Credentials',true);
    next();
});

var Schema = mongo.Schema;

var UserSchema = new Schema({
    name: { type: String },
    address: {type: String},
}, { versionKey: false});

var model = mongo.model('users', UserSchema, 'users');

app.post("/api/SaveUser", function(req, res) {
    var mod = new model(req, body);
    mod.save(function(err, data){
        if (err){
            res.send(err);
        } else {
            res.send({data: "Users save"});
        }
    });
});