javascript - Unable to pass a response form facebook to another function -

if view question thank in advance!, working on pulling data facebook.

i trying pull username facebook can use in later stage have embedded following code in fb root div.

i know retrieve works! not able pass on function returndata relative new javascript please me out? have tried

there alert in there check if retrieving data

<div id="fb-root"></div> <script type="text/javascript">       $(document).ready(function()      {         var appid = "121070974711874";          // if logging in facebook canvas application use url.         var redirecturl = "http://apps.facebook.com/bggressive";          // if logging in website this. sure add host           application's app domain list.          var redirecturl = window.location.href;          // if user did not grant app authorization go ahead , tell them that. stop code execution.         if (0 <= window.location.href.indexof ("error_reason"))         {              $(document.body).append ("<p>authorization denied!</p>");              return;         }          // when facebook sdk script has finished loading init        // sdk , login status of user. status        // reported in handler.        window.fbasyncinit = function()        {            fb.init({                      appid : appid,                      status : true,                      cookie : true,                      oauth : true            });            fb.getloginstatus (oncheckloginstatus);        };         (function(d)        {           var js, id = 'facebook-jssdk'; if (d.getelementbyid(id)) {return;}           js = d.createelement('script'); js.id = id; js.async = true;           js.src = "//connect.facebook.net/en_us/all.js";           d.getelementsbytagname('head')[0].appendchild(js);        }(document));          function oncheckloginstatus (response)        {           if (response.status != "connected")           {               top.location.href = "https://www.facebook.com/dialog/oauth?client_id=" + appid + "&redirect_uri=" + encodeuricomponent (redirecturl) + "&scope=user_photos,friends_photos";           }           else           {               fb.api('/me', function(response)                {                   pason = response.username                   alert(response.username)               });           }        }    });     function returndata()    {       = pason       return    };  </script> 

i think calling function returndata() @ random point can't do. reason is- variable pason assigned value asynchronously. so, have code in such way call returndata() after value assigned!

its not quite clear trying function returndata(). but, hope concept clear now.