Node JS Libraries

When dealing with authentication (e.g., cookies or JWT), you need to ensure CORS configuration allows credentials: Make sure that the client-side code also includes credentials in requests:

If you’re using other HTTP frameworks or libraries, you’ll need to manually handle CORS. Here’s a brief example using http module:

You can control how long browsers cache the preflight responses using the maxAge option:

You might want to dynamically determine whether to allow a request based on the origin. Here’s an example that allows origins based on a list or pattern:

If you are not using Express but another framework or no framework at all, you might need to handle CORS manually or use specific middleware. The general idea is similar: set appropriate headers in your HTTP responses.

For more complex scenarios, like allowing multiple origins, you can use a function for the origin option:

Browsers send preflight requests (OPTIONS requests) to check if the server allows the actual request. The cors middleware handles this for you, but if you need more control, you can set up custom handling:

You can configure CORS to be more specific about which origins are allowed and other settings. For example:

If you are using Express, you can set up CORS by including the cors middleware in your application. Here’s a basic example:

First, you need to install the cors package. You can do this using npm or yarn: or