Displaying a button with a varying background image, depending on whether the user is logged in (in the Unity3D Facebook integration with Coherent UI sample)

facebook_makebutton.js

var appID = '344764665598630';
var appURL = 'http://www.coherent-labs.com/sample.html';

if (window.location.hash.length == 0)
{
	// Not logged in
	
	$(function () {
		var button = $('<div id="fbButton" class="fbLogoDisabled"></div>');
		button.click(function () {
			var path = 'https://www.facebook.com/dialog/oauth?';
			var queryParams = {
				client_id: appID,
				redirect_uri: appURL,
				response_type: 'token,signed_request,code',
				scope: 'user_photos,publish_stream'
			};
			var url = path + $.param(queryParams);
			// redirect the view to the facebook authorization dialog
			window.location.href = url;
		});
		$('body').append(button);
	});
}
else
{
	// Logged in
	
	// Load the Facebook SDK source
	(function(d){
		var js, id = 'facebook-jssdk', ref = d.getElementsByTagName('script')[0];
		if (d.getElementById(id)) {return;}
		js = d.createElement('script'); js.id = id; js.async = true;
		js.src = "http://connect.facebook.net/en_US/all.js";
		ref.parentNode.insertBefore(js, ref);
	}(document));
	
	$(function () {
		var button = $('<div id="fbButton" class="fbLogoEnabled"></div>');
		$('body').append(button);
	});
}