facebook details in codebehind

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C#

Facebook-API

i am using facebook login on website which works only for developer account to login, so how to resolve it and how to get user email on code behind.

code I used is:

<div id="fb-root"></div>
<h2>Updated JS SDK example</h2><br />
<div id="user-info"></div>
<p><button id="fb-auth">Login</button>
<label id="lbemail"  runat="server"></label>
 </p>

<script type="text/javascript">
    window.fbAsyncInit = function () {
        FB.init({ appId: 'API',
            status: true,
            cookie: true,
            xfbml: true,
            oauth: true
        });

        function updateButton(response) {
            var button = document.getElementById('fb-auth');
            var email = document.getElementById('lbemail');
            if (response.authResponse) {
                //user is already logged in and connected
                var userInfo = document.getElementById('user-info');
                FB.api('/me', function (response) {
                    userInfo.innerHTML = '<img src="https://graph.facebook.com/'
	  + response.id + '/picture">' + response.name + response.user_location;
                    email.innerHTML = response.email;
                    button.innerHTML = 'Logout';


                });
                button.onclick = function () {
                    FB.logout(function (response) {
                        var userInfo = document.getElementById('user-info');
                        userInfo.innerHTML = "";
                    });
                };
            } else {
                //user is not connected to your app or logged out
                button.innerHTML = 'Login';
                button.onclick = function () {
                    FB.login(function (response) {
                        if (response.authResponse) {
                            FB.api('/me', function (response) {
                                var userInfo = document.getElementById('user-info');
                                userInfo.innerHTML =
                '<img src="https://graph.facebook.com/'
	        + response.id + '/picture" style="margin-right:5px"/>'
	        + response.name;
                            });
                        } else {
                            //user cancelled login or did not grant authorization
                        }
                    }, { scope: 'email' });
                }
            }
        }

        // run once with current status and whenever the status changes
        FB.getLoginStatus(updateButton);
        FB.Event.subscribe('auth.statusChange', updateButton);
    };

    (function () {
        var e = document.createElement('script'); e.async = true;
        e.src = document.location.protocol
    + '//connect.facebook.net/en_US/all.js';
        document.getElementById('fb-root').appendChild(e);
    } ());

</script>