Login with facebook email using facebook api

<a href="#" id="facebook-login">Login with facebook</a>
<p id="result"></p>

<script src="http://connect.facebook.net/en_US/all.js"></script>
<script type="text/javascript">
	 FB.init({
		appId:'your app key',
		cookie:true,
		status:true,
		xfbml:true
	 });
	$(document).ready(function() {
		$("#facebook-login").click(function(event) {
			event.preventDefault();
			FB.login(function(response) {
			  if (response.session) {
				if (response.perms) {
					// user is logged in and granted some permissions.
					// perms is a comma separated list of granted permissions
					FB.api('/me?fields=name,email', function (response) {
						var fb_name=response.name;
						var fb_email=response.email;
						var loadUrl="path to your login verification script";
						$.post( loadUrl, {email: fb_email}, function(status) {
							if(status=="success"){
								$('#result').html("You have successfully logged in with your facebook account");
							}
							else {
								$('#result').html("User haven't registered yet!");
							}
						});
					});
				}
				else {
				  $('#result').html("user is logged in, but did not grant any permissions");
				}
			  }
			  else {
				$('#result').html("user is not logged in");
			  }
			}, {perms:'email,status_update,publish_stream'});
		});
	});
</script>