Hi this seems to be the extra testing code which was left in script, which you can remove or we would remvoe in our update you can leave it for now .
If you check register.php
This is the code below registration form which generates the Facbeook button.
<?php if(get_option('facebook_login') == '1') { ?>
<center><fb:login-button scope="public_profile,email" size="xlarge" onlogin="checkLoginState();">
<?php _e("Register With Facebook"); ?>
</fb:login-button></center>
<?php } ?>
And in same file on top we have this code which includes facebook file and message returned from facebook for errors.
if(get_option('facebook_login') == '1') {
include('lib/includes/add_facebook.php');
echo '<div id="fb_return_msg"></div>';
}
Here is the facebook API login example which expect an API Code
<!DOCTYPE html>
<html>
<head>
<title>Facebook Login JavaScript Example</title>
<meta charset="UTF-8">
</head>
<body>
<script>
function statusChangeCallback(response) { // Called with the results from FB.getLoginStatus().
console.log('statusChangeCallback');
console.log(response); // The current login status of the person.
if (response.status === 'connected') { // Logged into your webpage and Facebook.
testAPI();
} else { // Not logged into your webpage or we are unable to tell.
document.getElementById('status').innerHTML = 'Please log ' +
'into this webpage.';
}
}
function checkLoginState() { // Called when a person is finished with the Login Button.
FB.getLoginStatus(function(response) { // See the onlogin handler
statusChangeCallback(response);
});
}
window.fbAsyncInit = function() {
FB.init({
appId : '{app-id}',
cookie : true, // Enable cookies to allow the server to access the session.
xfbml : true, // Parse social plugins on this webpage.
version : '{api-version}' // Use this Graph API version for this call.
});
FB.getLoginStatus(function(response) { // Called after the JS SDK has been initialized.
statusChangeCallback(response); // Returns the login status.
});
};
(function(d, s, id) { // Load the SDK asynchronously
var js, fjs = d.getElementsByTagName(s)[0];
if (d.getElementById(id)) return;
js = d.createElement(s); js.id = id;
js.src = "https://connect.facebook.net/en_US/sdk.js";
fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));
function testAPI() { // Testing Graph API after login. See statusChangeCallback() for when this call is made.
console.log('Welcome! Fetching your information.... ');
FB.api('/me', function(response) {
console.log('Successful login for: ' + response.name);
document.getElementById('status').innerHTML =
'Thanks for logging in, ' + response.name + '!';
});
}
</script>
// The JS SDK Login Button
<fb:login-button scope="public_profile,email" onlogin="checkLoginState();">
</fb:login-button>
<div id="status">
</div>
</body>
</html>
Details can be found here. https://developers.facebook.com/docs/facebook-login/web/
If you face problems setting up facebook login system you can send me your logins with your FTP and your website's API key from facebook and i would setup this for you and would solve the issues if there would be any but i guess many people are using it and its working fine for them.