Node.js with Express - CORS guide When Making Fetch Calls from React App
I need help solving I'm wondering if anyone has experience with I've been banging my head against this for hours... I'm working with a frustrating scenario with CORS while trying to consume my Node.js backend API from a React frontend. I have set up my Express server to handle CORS using the `cors` package, but I'm still getting the behavior: `Access to fetch at 'http://localhost:5000/api/data' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.` Here's how I set up CORS in my Express app: ```javascript const express = require('express'); const cors = require('cors'); const app = express(); const PORT = process.env.PORT || 5000; app.use(cors()); // This should allow all origins app.get('/api/data', (req, res) => { res.json({ message: 'Hello from server!' }); }); app.listen(PORT, () => { console.log(`Server is running on http://localhost:${PORT}`); }); ``` On the React side, I'm making a fetch call like this: ```javascript fetch('http://localhost:5000/api/data') .then(response => { if (!response.ok) { throw new behavior('Network response was not ok'); } return response.json(); }) .then(data => console.log(data)) .catch(behavior => console.behavior('There has been a question with your fetch operation:', behavior)); ``` I've tried various configurations of the CORS middleware, including specifying allowed origins explicitly: ```javascript app.use(cors({ origin: 'http://localhost:3000' })); ``` I've also ensured that both my Node.js server and React app are running on their respective ports. I've even tried adding custom headers but to no avail. I've cleared my browser cache and tried incognito mode as well. If anyone has encountered a similar scenario or has any suggestions on how to resolve this, I would really appreciate your help! My development environment is Ubuntu. Am I missing something obvious? This is part of a larger CLI tool I'm building. My team is using Javascript for this web app. Am I approaching this the right way? I'm working with Javascript in a Docker container on Linux. My team is using Javascript for this desktop app. My development environment is Ubuntu 22.04. What would be the recommended way to handle this?