How to get access token from FB.login method in javascript SDK

I need to get the access token from FB.login method in Javascript SDK. My login code is

FB.login(function(response) {
    if (response.session) {
        if (response.perms) {

        } else {
            // user is logged in, but did not grant any permissions
            alert("No Permission..");
        }
    } else {
        // user is not logged in
        alert("Please login to facebook");
    }
}, {perms:'read_stream,publish_stream,offline_access'});

Is there any way to get access token? I am able to get the access token using PHP.

You can get access token using FB.getAuthResponse()['accessToken']:

FB.login(function(response) {
   if (response.authResponse) {
     var access_token =   FB.getAuthResponse()['accessToken'];
     console.log('Access Token = '+ access_token);
     FB.api('/me', function(response) {
     console.log('Good to see you, ' + response.name + '.');
     });
   } else {
     console.log('User cancelled login or did not fully authorize.');
   }
 }, {scope: ''});

Edit: Updated to use Oauth 2.0, required since December 2011. Now uses FB.getAuthResponse(); If you are using a browser that does not have a console, (I'm talking to you, Internet Explorer) be sure to comment out the console.log lines or use a log-failsafe script such as:

if (typeof(console) == "undefined") { console = {}; } 
if (typeof(console.log) == "undefined") { console.log = function() { return 0; } }

response.session.access_token doesn't work in my code. But this works: response.authResponse.accessToken

     FB.login(function(response) { alert(response.authResponse.accessToken);
     }, {perms:'read_stream,publish_stream,offline_access'});

If you are already connected, simply type this in the javascript console:

FB.getAuthResponse()['accessToken']

https://developers.facebook.com/docs/facebook-login/login-flow-for-web/

{
    status: 'connected',
    authResponse: {
        accessToken: '...',
        expiresIn:'...',
        signedRequest:'...',
        userID:'...'
    }
}


FB.login(function(response) {
    if (response.authResponse) {
        // The person logged into your app
    } else {
        // The person cancelled the login dialog
    }
});

response.session doesn't work anymore because response.authResponse is the new way to access the response content after the oauth migration.
Check this for details: SDKs & Tools › JavaScript SDK › FB.login