Enable CORS

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.

The code to enable CORS in Next.js is very simple. In fact, you can enable it using the following code:

function withCors() {
  const headers = new Headers();
  headers.append('Access-Control-Allow-Origin', '*');
  headers.append(
    'Access-Control-Allow-Headers',
    'Origin, X-Requested-With, Content-Type, Accept, referer-path'
  );
  return headers;
}

Additionally, you need to handle OPTIONS requests appropriately.

import { NextRequest } from "next/server";
export async function GET(request: NextRequest) {
  if (request.method === `OPTIONS`) {
    return new Response(null, {
      headers: {
        'Access-Control-Allow-Origin': '*',
        'Access-Control-Allow-Methods': 'GET, HEAD, POST, PUT, DELETE',
      },
    });
  }
}

In your Makerkit codebase, this function is already available in the ~/core/middleware/with-cors.ts file.

To enable CORS, you can simply call it in your handler. If it fails, it will throw an exception with the appropriate HTTP status code.

import withCors from '~/core/middleware/with-cors';
export async function GET(request: NextRequest) {
  const headers = withCors();
  if (request.method === `OPTIONS`) {
    return new Response(null, {
      headers,
    });
  }
}