How do I configure CORS headers for my web application?

How do I configure CORS headers for my web application?

To configure CORS headers, you need to set the appropriate headers in your server's response. Common headers include 'Access-Control-Allow-Origin', 'Access-Control-Allow-Methods', and 'Access-Control-Allow-Headers'. What server technology are you using?

I'm using Express.js for my Node.js application.

Great! In Express.js, you can use the 'cors' middleware. First, install it using npm: npm install cors. Then, require it in your app and use it like this:

const cors = require('cors');
app.use(cors());

This will allow all origins. You can customize it further if needed.

How can I restrict it to specific origins?

You can restrict it by passing 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'. You can also pass an array of origins.

What about preflight requests?

Preflight requests are automatically handled by the cors middleware. It will respond to OPTIONS requests with the appropriate headers. Just ensure your server is set up to handle OPTIONS requests if you have custom logic.