<section>
    <input type="text" id="_username" name="_username" placeholder="Email Address" />
    <input type="password" id="_password" name="_password" placeholder="Password" />
    <footer>
        <button data-iziModal-close>Cancel</button>
        <button id="form_login" class="submit">Log in</button>
    </footer>
</section>

$('#form_login').on('click', function(event) {
    event.preventDefault();
    $.ajax({
        type : 'post',
        url: '/login',
        data: '_username=abc&_password=temp123',
        success : function(response) {
            console.log(response);
        }
    });
});

services:
    acme.security.authentication_handler:
        class: UserBundleHandlerAuthenticationHandler
        public: false
        arguments: ["@router", '@session']

security:
    encoders:
        UserBundleEntityUser: bcrypt
    providers:
        in_memory:
            memory: ~

    firewalls:
        dev:
            pattern: ^/(_(profiler|wdt)|css|images|js)/
            security: false
        main:
            anonymous: ~
            form_login:
                check_path: login
                success_handler: acme.security.authentication_handler
                failure_handler: acme.security.authentication_handler
    access_control:
        - { path: ^/, roles: IS_AUTHENTICATED_ANONYMOUSLY }

<?php

namespace UserBundleHandler;

use SymfonyComponentHttpFoundationResponse;
use SymfonyComponentHttpFoundationRedirectResponse;
use SymfonyComponentRoutingRouterInterface;
use SymfonyComponentHttpFoundationSessionSession;
use SymfonyComponentSecurityCoreAuthenticationTokenTokenInterface;
use SymfonyComponentSecurityCoreExceptionAuthenticationException;
use SymfonyComponentHttpFoundationRequest;
use SymfonyComponentSecurityCoreSecurityContextInterface;
use SymfonyComponentSecurityHttpAuthenticationAuthenticationSuccessHandlerInterface;
use SymfonyComponentSecurityHttpAuthenticationAuthenticationFailureHandlerInterface;

class AuthenticationHandler implements AuthenticationSuccessHandlerInterface, AuthenticationFailureHandlerInterface
{
    private $router;
    private $session;

    public function __construct(RouterInterface $router, Session $session)
    {
        $this->router  = $router;
        $this->session = $session;
    }

    public function onAuthenticationSuccess( Request $request, TokenInterface $token )
    {
        if ($request->isXmlHttpRequest()) {
            $array = array('success' => true);
            $response = new Response(json_encode($array));
            $response->headers->set('Content-Type', 'application/json');
            return $response;
        } else {
            if ( $this->session->get('_security.main.target_path')) {
                $url = $this->session->get('_security.main.target_path');
            } else {
                $url = $this->router->generate('home');
            }
            return new RedirectResponse($url);
        }
    }

    public function onAuthenticationFailure( Request $request, AuthenticationException $exception )
    {
        // if AJAX login
        if ($request->isXmlHttpRequest()) {
            $array = array('success' => false, 'message' => $exception->getMessage()); // data to return via JSON
            $response = new Response(json_encode( $array ));
            $response->headers->set('Content-Type', 'application/json');
            return $response;
        // if form login
        } else {
            // set authentication exception to session
            $request->getSession()->set(SecurityContextInterface::AUTHENTICATION_ERROR, $exception);
            return new RedirectResponse($this->router->generate('login'));
        }
    }
}

/**
 * @Route("/login", name="login")
 * @Template()
 */
public function loginAction()
{
    $authenticationUtils = $this->get('security.authentication_utils');
    $error = $authenticationUtils->getLastAuthenticationError();
}