How can CORS (Cross-Origin Resource Sharing) preflight requests be handled effectively to allow cross-origin requests while maintaining security?

CORS (Cross-Origin Resource Sharing) is a browser security mechanism that restricts web pages from making requests to a different domain than the one that served the web page. A CORS preflight request is a preliminary OPTIONS request that the browser sends to the server to determine if the actual cross-origin request is safe to send. It's sent automatically by the browser when the cross-origin request meets certain conditions, such as using HTTP methods other than GET, HEAD, or POST, or setting custom headers. To handle CORS preflight requests effectively and maintain security: 1. Respond to OPTIONS Requests: Your server must be configured to respond to OPTIONS requests for the routes that need to support cross-origin requests. This is typically done using middleware like `cors` in Express.js. 2. Set Appropriate CORS Headers: In the response to the OPTIONS request, you must set the appropriate CORS headers to i....