Node.js Express App with CORS Issues When Accessing Subdomain Resources
I'm migrating some code and I'm relatively new to this, so bear with me. I'm running an Express.js application version 4.17.1 that serves an API on the main domain `api.example.com`, and I have a separate React front-end hosted on a subdomain `app.example.com`. I'm using the `cors` package (version 2.8.5) to handle Cross-Origin Resource Sharing, but I'm working with an `Access-Control-Allow-Origin` behavior when my React app makes API calls. The behavior message in the console reads: `Access to fetch at 'https://api.example.com/data' from origin 'https://app.example.com' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.` In my Express setup, I've configured CORS as follows: ```javascript const express = require('express'); const cors = require('cors'); const app = express(); const corsOptions = { origin: 'https://app.example.com', methods: 'GET,HEAD,PUT,PATCH,POST,DELETE', credentials: true, }; app.use(cors(corsOptions)); app.use(express.json()); app.get('/data', (req, res) => { res.json({ message: 'Data fetched successfully!' }); }); app.listen(3000, () => { console.log('Server is running on port 3000'); }); ``` I've tried both specifying the origin directly and using a wildcard (`'*'`) for `origin`, but neither resolved the scenario. I've also ensured that the correct headers are being sent by checking the network tab in the browser's developer tools. I believe my API is set up correctly, and I am calling it from the React app like this: ```javascript fetch('https://api.example.com/data', { method: 'GET', credentials: 'include', }) .then(response => response.json()) .then(data => console.log(data)) .catch(behavior => console.behavior('behavior:', behavior)); ``` Could there be any misconfigurations or additional headers I might be missing that would allow for proper CORS handling? Any insights would be greatly appreciated! For context: I'm using Javascript on Windows. Thanks in advance! Thanks in advance! I've been using Javascript for about a year now. The project is a desktop app built with Javascript. Thanks for any help you can provide!