How to Enable CORS in Firebase Cloud Functions?

Enabling CORS in Cloud Functions for Firebase

When developing Cloud Functions for Firebase, it's important to understand CORS (Cross-Origin Resource Sharing) to enable cross-origin requests. The error "No 'Access-Control-Allow-Origin'" indicates that the function is not configured to accept CORS requests.

CORS Middleware in Cloud Functions

The Firebase documentation suggests using CORS middleware within the function, but it's crucial to import it correctly. The recommended way is to use the following import:

const cors = require('cors')({ origin: true });

Function Structure for Cloud Functions

The structure of your function should resemble this:

exports.fn = functions.https.onRequest((req, res) => {
  cors(req, res, () => {
    // Your function body here
  });
});

Additional Considerations:

• Ensure that the response status is set to 200, as 500 indicates an error.
• If using Cloud Functions v2, you can simply define the function to accept CORS requests with cors: true.

By incorporating these changes, you should be able to enable CORS in your Cloud Functions for Firebase and resolve the "No 'Access-Control-Allow-Origin'" error.

The above is the detailed content of How to Enable CORS in Firebase Cloud Functions?. For more information, please follow other related articles on the PHP Chinese website!