CORS (Cross-Origin Resource Sharing) is a security feature implemented by web browsers to restrict web pages from making requests to a different domain than the one that served the web page. In the context of Electron, which combines web technologies with Node.js, the handling of CORS can differ from traditional web applications.

1. CORS Enforcement in the Electron Renderer Process

In Electron, CORS is enforced in the renderer process similarly to how it is in a regular web browser. However, there are some nuances:

Development vs. Production: When you run your application in development mode (e.g., using Vite), it behaves like a typical web application, and CORS policies are strictly enforced. This is why you see pre-flight requests when your app is running on localhost:5173

Packaged App: When you package your app, it often runs from the file:// protocol. In this case, CORS restrictions can be less strict. The file:// protocol is treated differently by browsers, and many CORS checks may not apply. This is why you might not see pre-flight requests in your packaged app.

2. CORS and the file:// Protocol

When your Electron app is running from the file:// protocol, CORS is generally not enforced in the same way as it is for HTTP/HTTPS requests. This means that:

Requests made from a file:// origin may not trigger CORS checks, which can lead to different behavior compared to when running in a web server context (like localhost:5173).

If your application is making requests to a remote server, those requests may not be subject to the same CORS restrictions as they would be in a browser context.

3. Impact of nodeIntegration

The nodeIntegration flag allows you to use Node.js APIs directly in the renderer process. When nodeIntegration is enabled:

You can make requests using Node.js modules (like http, https, or axios) that do not enforce CORS, as they are not subject to the same restrictions as browser-based requests.

If you are using fetch or XMLHttpRequest in the renderer process with nodeIntegration enabled, CORS will still apply to those requests, but you may have more flexibility in how you handle requests using Node.js APIs.

Hopefully this helps..