前端未与后端通信

Question

Error image 我认为前端没有与后端通信，但是由于我是MEAN新手，所以找不到问题。非常感谢您为解决该问题提供的帮助。

这是server.js文件。

    const app = require("./backend/app");
    const debug = require("debug")("node-angular");
    const http = require("http");
    const normalizePort = val => {
      var port = parseInt(val, 10);
      if (isNaN(port)) {
        // named pipe
        return val;
      }
      if (port >= 0) {
        // port number
        return port;
      }
      return false;
    };

    const onError = error => {
      if (error.syscall !== "listen") {
        throw error;
      }
      const bind = typeof addr === "string" ? "pipe " + addr : "port " + port;
      switch (error.code) {
        case "EACCES":
          console.error(bind + " requires elevated privileges");
          process.exit(1);
          break;
        case "EADDRINUSE":
          console.error(bind + " is already in use");
          process.exit(1);
          break;
        default:
          throw error;
      }
    };

    const onListening = () => {
      const addr = server.address();
      const bind = typeof addr === "string" ? "pipe " + addr : "port " + port;
      debug("Listening on " + bind);
    };

    const port = normalizePort(process.env.PORT || "3000");
    app.set("port", port);
    const server = http.createServer(app);
    server.on("error", onError);
    server.on("listening", onListening);
    server.listen(port);

这是app.js文件。

    const express = require('express');
    const bodyParser = require('body-parser');
    const mongoose = require('mongoose');
    const cors = require('cors');

    const userRoutes = require('./routes/user');

    const app = express();

    mongoose.connect('mongodb://localhost:27017/shopping-cart')
    .then(() =>{ console.log('Database connected');
    }).catch(() => {
      console.log('Connnection failed');
    });

    app.use(bodyParser.json());
    app.use(bodyParser.urlencoded({extended: false}));
    app.use(cors());

    app.use('/user', userRoutes);

    module.exports = app;

服务提供商文件。

    import { AuthData } from './auth-data.model';
    import { Injectable } from '@angular/core';
    import { HttpClient } from '@angular/common/http';

    @Injectable({ providedIn: 'root'})

    export class AuthService {

    constructor(private http: HttpClient) {}

    createUser(email: string, password: string) {

      const authData: AuthData = { email: email, password: password };

    this.http.post('http://localhost:3000/user/register', authData)
    .subscribe(response => {
    console.log(response);
    });
    }
    }

用于创建用户的用户路线。

    const express = require('express');
    const User = require('../models/user');
    const bcrypt = require('bcryptjs');
    const router = express.Router();

    router.post('/register'), (req, res, next) => {
      bcrypt.hash(req.body.password, 10).then(hash => {
        const user = new User({
          email: req.body.email,
          password: hash
        });
        user.save()
        .then(result => {
          res.status(201).json({
            message: 'User Created',
            result: result
          });
        })
        .catch(err => {
          res.status(500).json({
            error: err
          });
        });
      });

    };
    module.exports = router;

在注册新用户时，它应该创建一个新用户，但找不到404错误