PromiseFaceBook.js

var resolved = false;
var resolving;
/* global FB */
var fbResolver = new Promise((resolve,reject) => {
	if(resolved)
		return resolve();
	
	resolving = resolve;
});

window.fbAsyncInit = function() {
	resolved = true;
	resolving();
}

/* exported */
function PromiseFaceBook(appId,version,init) {
	if(!init)
		init = { cookie: true,xfbml: true };

	init.version = version || "v2.5";
	init.appId = appId;
	return fbResolver.then(() => {
		FB.init(init);
		return new Promise((resolve,reject) => {
			FB.getLoginStatus(function(response) {
				if(response.status !== 'connected')
					return FB.login((response) => PromiseFaceBook(appId,version,init).then(resolve));

				resolve(response);
			});
		});
	},console.error);
}