Snippet de Ionic para hacer login con FB.

fb_login.js

angular.module('starter', ['ionic'])

.run(function($ionicPlatform) {
  $ionicPlatform.ready(function() {
    if (window.cordova && window.cordova.plugins.Keyboard) {
      cordova.plugins.Keyboard.hideKeyboardAccessoryBar(true);
      cordova.plugins.Keyboard.disableScroll(true);
    }

    if (window.StatusBar) {
      StatusBar.styleDefault();
    }
  });
}).controller('LoginController', ['$scope', function($scope) {
  $scope.userData = 'None';
  $scope.token = 'None';
  $scope.fbLogin = function() {
    facebookConnectPlugin.login(['public_profile'], successFBLogin, errorFBLogin);
  };

  $scope.fbLogout = function() {
    facebookConnectPlugin.logout(function() {
      alert('logged out');
    }, errorFBLogin);
  };

  var successFBLogin = function(userData) {
    $scope.userData = userData;
    console.log("UserInfo: ", userData);
    facebookConnectPlugin.getAccessToken(function(token) {
      $scope.token = token;
      console.log("Token: " + token);
    });
  };

  var errorFBLogin = function(error) {
    console.error(error);
  };
}]);