我是nodejs的新手，在尝试加载（http：//localhost：3000/api/auth/register）时，我不知道为什么会出现（无法获取/api/auth/register）
auth.js文件

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

//Register
router.post('/register', async (req,res)=>{
    const newUser = new User(
        {
            username: req.body.username,
            email: req.body.email,
            password: req.body.password,
        }
    );
    try {
        const user = await newUser.save();
        res.status(200).json(user);
    }
    catch (err) {
        res.status(500).json(err);
    }
});

module.exports = router;

index.js文件

const express = require('express');
const mongoose = require('mongoose');
const dotenv = require('dotenv');
const helmet = require('helmet');
const morgan = require('morgan');
const userRoute = require('./routes/users');
const authRoute= require('./routes/auth');

const app = express();

dotenv.config();

mongoose.connect(process.env.MONGO_URL,{useNewUrlParser:true},()=>{
    console.log("Connected to DB");
});

//middleware
app.use(express.json());
app.use(helmet());
app.use(morgan('common'));

app.use('/api/users',userRoute);
app.use('/api/auth',authRoute);

app.listen(3000,()=>{
    console.log("backend running");
});

File Structure Diagram