title: How to define CSRF token in ajax call in Cakephp 3. Also How CSRF can be off for some ajax requests
body: <p>In Cakephp3 when the Csrf component is enabled. How I can use it in ajax call.
  In this <code>beforeSend</code> parameter of ajax csrf token is set in header. What is the value of <code>csrfToken</code>. As it gives error</p>
  
  <blockquote>
    <p>csrfToken is not defined</p>
  </blockquote>
  
  <pre><code>beforeSend: function(xhr){
      xhr.setRequestHeader('X-CSRF-Token', csrfToken);
  },
  </code></pre>
  
  <p>Also how can I disable Csrf component for some ajax calls.</p>