带有CORS中间件的ExpressJS服务器上的CORS错误已经添加

Question

我有一个在AWS Lightsail上托管的前端和Express JS服务器，该服务器将Ubuntu与Nginx一起使用。

服务器设置为反向代理。 配置

location /api/ { 
proxy_pass http://localhost:4000/api/;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection 'upgrade';
proxy_set_header Host $host;
proxy_cache_bypass $http_upgrade;
}

这是我正在尝试从客户端发出发布请求（登录）以表达

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource 
at http://localhost:4000/api/users/login. (Reason: CORS request did not succeed). Status 
code: (null).

的

const cors = require('cors');
const app = express();

const corsOption = {origin: "http://18.193.59.75:80"};

app.options("/*", function(req, res, next){ 
  res.header('Access-Control-Allow-Origin', '*'); 
  res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');
  res.header('Access-Control-Allow-Headers', 
  'Content-Type, Authorization, Content-Length, X-Requested-With');
  res.send(200);});

//app.use(cors(corsOptions));
//app.options('*', cors(corsOptions));

Answer 1

添加next（）处理程序，如下所示，查看是否解决了您的问题。

const cors = require('cors');
const app = express();

// const corsOption = {origin: "http://18.193.59.75:80"};

var corsOptions = function(req, res, next){ 
    res.header('Access-Control-Allow-Origin', '*'); 
    res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');
    res.header('Access-Control-Allow-Headers', 
    'Content-Type, Authorization, Content-Length, X-Requested-With');
     next();
}

app.use(corsOptions);

Answer 2

我仍然在使用CORS上的移动设备上遇到问题，我删除了所有配置
'http：// localhost：4000'我的服务器正在运行但它在服务器上运行，因此要到达它，我必须称其为http://18.193.59.75/api/ Endpoint和NGINX将重定向到'http：// localhost：4000'带代理通行证。

这是我的nginx config

server {
  listen 80;
  listen [::]:80;

  server_name _;
  location / {
     root /var/www/website/client;
     try_files $uri /index.html;
  }

  location /api { 
      proxy_pass http://localhost:4000;
  }

和我的index.js

const express = require('express');
const cors = require('cors');
const app = express();

// var corsOptions = function(req, res, next){ 
//     res.header('Access-Control-Allow-Origin', '*'); 
//     res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');
//     res.header('Access-Control-Allow-Headers', 
//     'Content-Type, Authorization, Content-Length, X-Requested-With');
//      next();
// }

// app.use(corsOptions);

app.use(cors());

app.use(aux);

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


app.use('/api/appointments', require('./api/appointmnets'));
app.use('/api/users', require('./api/users'));

app.get('/test', (req, res) => {
    res.json({'test' : 'successed'})
})

const PORT = process.env.PORT || 4000;

app.listen(PORT, () => {
    console.log(`App listens to port ${PORT}`);
})

。

const domain = 'http://18.193.59.75:80/api/';
const domain = 'http://localhost:80/api';    //wronge