I am creating a website that will allow users to embed widgets on their own blogs and websites. I have previously used the Facebook SDK to allow URLs to be shared from defined websites, but now I need this to work for any website. However, when creating a Facebook app "App domains" have to be specified/whitelisted and I can't see how to bypass this restriction. Can anybody help please?

FB.init({
    appId            : 'xxxxxxxxxxx',
    autoLogAppEvents : true,
    xfbml            : true,
    version          : 'v3.3'
});
FB.ui({
    method: 'share',
    display: 'popup',
    href: url,
}, function(response){});