Enable CORS | Next.js Firebase SaaS Kit

Enabling CORS is required if you want to allow serving HTTP request to external clients. For example, if you want to expose an API to some consumers: JS libraries, headless clients, and so on.

To enable CORS, you can use the with-cors middleware in two different ways.

You can simply call it in your handler:

import withCors from '~/core/middleware/with-cors';
function apiHandler(
  req: NextApiRequest,
  res: NextApiResponse
) {
    withCors(res);
    // your logic
}
export default apiHandler;

Alternatively, you can use it with withPipe:

import withCors from '~/core/middleware/with-cors';
function handler(
  req: NextApiRequest,
  res: NextApiResponse
) {
   // your logic
}
export default withPipe(
  withCors,
  apiHandler
);

Additionally, you need to respond to OPTIONS request appropriately.

export function handler(
  req: NextApiRequest,
  res: NextApiResponse
) {
  withCors(res);
  if (req.method === `OPTIONS`) {
     // add the method you want to allow
     res.setHeader('Access-Control-Allow-Methods', 'GET');
     return res.end();
  }
}