Httprequest未收到来自快速路由器的响应

路由器的响应"/>

Httprequest未收到来自快速路由器的响应

我正在尝试启动XMLHttprequest并希望接收来自放置在我app.js文件中的快速路由的响应，但是该路由不起作用。任何人都可以帮助出什么问题吗以下是我的两个差异文件中的代码

文件1

       function signup_data_validation() {
           const data = {
           fname: 'Nasir',
           lname: 'Khatri'
           };

           const xhr = new XMLHttpRequest();
           const url = '../app.js/customers';
           const string_data = JSON.stringify(data);

           xhr.responseType = 'json';
           xhr.onreadystatechange = () => {
           if(xhr.readyState === XMLHttpRequest.DONE) {
           console.log(this.responseType);
           }
           }
           xhr.open('POST', url);
           xhr.send(string_data);
           }

           signup_data_validation();

文件2：

const express = require('express');
const sqlite3 = require('sqlite3');
const db = new sqlite3.Database('./miclothing');
const app = express();
app.use(express.static('public'));   // web resources location

const PORT = process.env.PORT || 4001;

app.use((req, res, next) => {
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Authorization");
    next();
});

app.post('/app.js/customers', (req, res, next) => {
    const query = req.query;
    query = JSON.parse(query);
    console.log(query.name);
    console.log()
    res.send("Done");
})

app.listen(PORT, () => {
    console.log(`Sever is listening at ${PORT}`);
});

在文件1]中，将const url = '../app.js/customers'更改为服务器的URL。

const url = 'http://localhost:4001/app.js/customers'

如果服务器未在侦听4001，则可以更改端口