How can I implement CORS in my Express.js application?

How can I implement CORS in my Express.js application?

You can use the cors middleware in Express.js. First, install it using npm: npm install cors. Then, require it in your app and use it as middleware.

Can you show me a code example?

Sure! Here's a simple example:

const express = require('express');
const cors = require('cors');

const app = express();
app.use(cors()); // Enable CORS for all routes

app.get('/api/data', (req, res) => {
  res.json({ message: 'This is CORS-enabled for all origins!' });
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

What if I want to restrict CORS to specific domains?

You can pass an options object to the cors middleware. For example:

app.use(cors({ origin: 'https://example.com' }));
``` This will only allow requests from `https://example.com`.