Node.js Express Middleware Order Causing CORS Issues with Axios Requests
I'm getting frustrated with I'm facing a frustrating issue with CORS while using Axios in my Node.js application with Express. I have a simple Express server set up that serves an API and I need to allow requests from my front-end application running on a different port. I installed the `cors` package and set it up as middleware, but I'm still getting a CORS error in the browser console. My setup looks like this: ```javascript const express = require('express'); const cors = require('cors'); const app = express(); // Middleware setup app.use(express.json()); app.use(cors()); // CORS middleware app.get('/api/data', (req, res) => { res.json({ message: 'Hello World' }); }); const PORT = 3000; app.listen(PORT, () => { console.log(`Server running on port ${PORT}`); }); ``` On the client side, I'm using Axios to make the request: ```javascript axios.get('http://localhost:3000/api/data') .then(response => { console.log(response.data); }) .catch(error => { console.error('Error fetching data:', error); }); ``` When I make this request from my front-end application (running on port 4000), I get the following error in the browser: ``` Access to XMLHttpRequest at 'http://localhost:3000/api/data' from origin 'http://localhost:4000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. ``` I've tried moving the `cors()` middleware to different positions, but it hasn't resolved the issue. I'm also aware that the order of middleware in Express matters, and I've ensured that `cors()` is called before defining any routes. Additionally, I have checked that my browser is not caching the old response. I've even tried specifying the origin explicitly in the CORS configuration: ```javascript app.use(cors({ origin: 'http://localhost:4000' })); ``` Still, the same error persists. What could I be missing here? Is there a specific configuration or setup I’m overlooking that’s causing this CORS issue? I would appreciate any guidance on how to resolve this. For reference, this is a production desktop app. Has anyone dealt with something similar?