Access to my Node.js Express API has been blocked by CORS policy-CodePudding

I am currently creating an angular web app, that communicates with a node.js backend with express. When I make a GET or POST request to the backend, i get this error message:

Access to XMLHttpRequest at 'http://localhost:9999' from origin 'http://localhost:4200' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

After a quick research I added app.use(cors()) to my index.ts file, but It doesn't seem to work. This is my index.ts file:

import { IoContainer } from './core/ioc/ioc.container';
import { LoggerService } from './core/services/logger.service';
import * as express from 'express';
import 'reflect-metadata';
import { InversifyExpressServer } from 'inversify-express-utils';
import { DatabaseService } from './core/services/database.service';
import { appendFile } from 'fs';

const cors = require('cors');

const container = new IoContainer();
container.init();

const logger = container.getContainer().resolve(LoggerService);
const databaseService = container.getContainer().resolve(DatabaseService);

const server = new InversifyExpressServer(container.getContainer());

databaseService.initialize().then(() =>{
    const app = server.build();
    app.use(cors());
    app.listen(9999);
    logger.info("Server listening on port 9999");
}).catch(() =>{
    logger.error("Error while starting express server");
})

Is there any other solution to this problem?

CodePudding user response：

add below line after app.use(cors()); may fix the problem

app.options('*', cors());

also you can put specific ip address instead *.

CodePudding user response：

I have found a solution to my problem now. I had to add the code inside of the server.setConfig() function like this:

server.setConfig((app) => {
    var cors = require('cors');
    app.use(cors({origin: `*`}));
    app.options('https://localhost:4200', cors());
});