记录express学习中遇到的问题

1.express解决跨域问题

1.在express项目的启动文件app.js设置：

const express = require('express');
const app = express();
const host = '127.0.0.1'
const port = 3000
//在所有请求发起之前进行拦截处理跨域问题
app.all('*', function(req, res, next) {
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "X-Requested-With");
    res.header("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");
    res.header("X-Powered-By",' 3.2.1')
    res.header("Content-Type", "application/json;charset=utf-8");
    next();
});

//.......
//中间部分为路由等业务代码

//监听server
const server = app.listen(port, host, () => {
   console.log(`server is started on ${host} : ${port} by zhangqianfeng`)
})

2.在前端请求:

        axios.get("http://127.0.0.1:3000/user/userdemo?name=123&password=zqf").then(res => {
            console.log(res.data);
        }).catch(err => {
            console.log(err);
        })