This script allows cross-domain JavaScript AJAX calls using GET and POST (and propably other methods) to any server by acting as a proxy.
In an example where JavaScript on www.webhost.com would like to make an AJAX request to an resource on api.server.com (say http://api.server.com/resource.json) but cannot because of cross domain security restrictions, the request can be made via the proxy.
The proxy accepts one paramater: url, the URL requested. So, place the script on a PHP host and from JavaScript call something like:
http://www.phphost.com/php-proxy/index.html?url=http://api.server.com/resource.json
By default, CORS is enabled on the script, meaning any domain can call the script. To limit calls to only your host (recommended), comment out the line enable_cors(); or modify the script as needed.