Failed to load http://localhost:8090/category/lists: The value of the 'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' when the request's credentials mode is 'include'. Origin 'http://localhost:8081' is therefore not allowed access. The credentials mode of requests initiated by the XMLHttpRequest is controlled by the withCredentials attribute.

const express = require('express')
const app = express()
const cors = require('cors') // 此处我的项目中使用express框架，跨域使用了cors npm插件
app.use(cors{
   credentials: true, 
   origin: 'http://localhost:8081', // web前端服务器地址
   // origin: '*' // 这样会出错
  })

import axios from 'axios'
// 创建axios实例
const service = axios.create({
 baseURL: process.env.BASE_API, // node环境的不同，对应不同的baseURL
 timeout: 5000, // 请求的超时时间
 //设置默认请求头，使post请求发送的是formdata格式数据// axios的header默认的Content-Type好像是'application/json;charset=UTF-8',我的项目都是用json格式传输，如果需要更改的话，可以用这种方式修改
 // headers: { 
 // "Content-Type": "application/x-www-form-urlencoded"
 // },
 withCredentials: true // 允许携带cookie
})
// 发送请求前处理request的数据
axios.defaults.transformRequest = [function (data) {
 let newData = ''
 for (let k in data) {
 newData += encodeURIComponent(k) + '=' + encodeURIComponent(data[k]) + '&'
 }
 return newData
}]
// request拦截器
service.interceptors.request.use(
 config => {
 // 发送请求之前，要做的业务
 return config
 },
 error => {
 // 错误处理代码
 
 return Promise.reject(error)
 }
)
// response拦截器
service.interceptors.response.use(
 response => {
 // 数据响应之后，要做的业务
 return response
 },
 error => {
 return Promise.reject(error)
 }
)
export default service

import fetch from '@/utils/fetch'
fetch({
 method: 'get',
 url: '/users/list'
})
 .then(res => {
 cosole.log(res)
})