Cross-Domain requests in Javascript

A detailed explanation can be found on my blog

In order to run the examples:

• Install node.
• Execute npm install in the root folder of the project (where the package.json file is located). This will install all the required dependencies.
• Execute run_servers.bat in one of the subfolders, this will start 2 web servers with a different origin (the port numbers differ).
• Use your browser to navigate to localhost:3000. The web pages will perform cross-domain requests on page load.
• Inspect the results in your browser window and in the server consoles.

The project illustrates the following scenarios:

1. CrossDomainNotAllowedByDefault: Demonstrates failing cross-origin requests.
2. JSONP: Demonstrates a simple cross-origin GET request with a server that supports JSONP.
3. Proxy: Demonstrates a work-around for cross-origin requests by having a local proxy server in the same domain.
4. CORS: Demonstrates a whitelist approach servers can use to allow cross-origin requests.
5. iframe and postMessage: demonstrates a sandboxed client-side proxy mechanism using window.postMessage and iframes. Note that this approach can also be used with other cross-domain request techniques to limit potential security leaks.

The examples are written in express, a web application framework for node.js and some jQuery on the client.