Test Your CORS Proxy Setup Online CORS Proxy Tester tool for network operations.

Under the hood, it uses the Fetch API to send HTTP requests to the specified URL, first attempting an OPTIONS request with the mode set to 'cors' to retrieve the CORS headers. If this fails, it falls back to a simple GET request with the same mode. The response from the server is then parsed to extract relevant CORS headers, including Access-Control-Allow-Origin, Access-Control-Allow-Methods, and Access-Control-Max-Age, which are stored in a CorsResult object. This object contains properties such as allowOrigin, allowMethods, and maxAge, which are used to determine whether the resource is accessible from the current origin. The tool utilizes React hooks, specifically useState and useCallback, to manage state and handle changes to the input URL. When the user submits a URL for testing, the handleTest function is called, which updates the state with the result of the CORS test, including the extracted headers and a status code.

The CorsResult object is then used to render the results in a user-friendly format, displaying the values of the CORS headers and indicating whether the resource is accessible. The tool also uses React components, such as InputWithHelp, to provide a mobile-friendly interface for users to input URLs and view test results. In terms of data structures, it relies on JavaScript objects and arrays to store and manipulate data, with the CorsResult object being a key part of this process. By using modern JavaScript features like ES6+ syntax and React hooks, the tool is able to provide a fast and efficient way to test CORS headers and debug cross-origin request issues. The Fetch API is used in conjunction with the 'cors' mode to ensure that requests are made with the correct credentials and headers, allowing for accurate testing of CORS policies.