How to let Facebook Login button redirect to a particular URL

Question

This is the info on Facebook Login button

http://developers.facebook.com/docs/guides/web/

So it will render a Login button, and a user can click on it to log

Answer 1

FBML option: This should give you the functionality you want (with xfbml:true in FB.init):

<fb:login-button autologoutlink="true" onlogin="OnRequestPermission();">
</fb:login-button>

When the user is logged in, it changes to "Log Out." Also, if the user has not granted permissions to the app, it pops-up the request permission dialog.

Custom option: If you don't like using FBML, you can make your own Facebook login button like this:

HTML:

<button id="THE_BUTTON">Login</button>

Javascript:

FB.init({appId: 'YourAPPID', status: true, cookie: true, xfbml: true, oauth : true});
FB.getLoginStatus(function(response) {
    if (response.status.toString().indexOf("connected")>-1) {
        initAll(); //User is connected and granted permissions
        FB.api("/me", function (response) {
            document.getElementbyId("THE_BUTTON").value = 
                                            "Logged in as " + response.name;
        });
    } else { 
        // This URL is specially formed to ask permissions for your app. You change the 
        // permissions and your appID
        //redirect_uri = Change this to your desired callback URL
        top.location=window.location="http://www.facebook.com/dialog/oauth/?scope=read_stream,publish_stream,friends_photos,friends_activities&client_id="yourAPPID(nobrackets)"&redirect_uri=http://apps.facebook.com/filtered_feed/&response_type=code";
    }
});

So if the user is logged in, the button will be replaced with "Logged in as user's name." Otherwise, the OAuth Dialog will appear.

Answer 2

1) You can also redirect on login using some code like this (note the auth.login event):

 <script src="http://connect.facebook.net/en_US/all.js">
  </script>
  <script>
      FB.init({
          appId: '??????????????', cookie: true,
          status: true, xfbml: true
      });
      FB.Event.subscribe('auth.login', function () {
          window.location = "http://example.com";
      });
  </script>
  <fb:login-button>
     Login with Facebook
  </fb:login-button>

2) To determine whether to show or hide the login button, you can use FB.getLoginStatus to discover whether the user is logged in. The following page might be of use: http://developers.facebook.com/docs/reference/javascript/FB.getLoginStatus/