角度：CORS飞行前响应未成功[重复]

Question

大家好,，

我的用户注册应用程序有问题，希望你们能帮我弄清楚发生了什么：

我使用的是MongoDb、Express、Angular和NodeJs，这就是它在app.js中的外观（我还包括Firefox和Chrome中显示的错误截图）。先谢谢你

var express = require('express');
var bodyParser = require('body-parser');


var app =express();
var user_routes = require('./routes/user');
var follow_routes = require('./routes/follow');
var publication_routes = require('./routes/publication');
var message_routes = require('./routes/message');

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

app.use((req, res, next) => {
res.header('Access-Control-Allow-Origin', '*');
res.header('Access-Control-Allow-Headers', 'Authorization, X-API-KEY, Origin, X-Requested-With, Content-Type, Accept, Access-Control-Allow-Request-Method');
res.header('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, DELETE');
res.header('Allow', 'GET, POST, OPTIONS, PUT, DELETE');
next();

}); 

app.use('/api', user_routes);
app.use('/api', follow_routes);
app.use('/api', publication_routes);
app.use('/api', message_routes);

module.exports = app;

Answer 1

您应该添加CORS标题-请参阅https://enable-cors.org/server_expressjs.html

Answer 2

使用npm cors包到白名单url或允许任何源请求。