title: Knowing when Google Analytics has loaded when loaded via Google Tag Manager
body: <p>We're using GTM to load Universal Analytics and I want to send some custom events from js to GA.
  So I need to do something like this:</p>
  
  <pre><code>ga('send', {
      hitType: 'event',
      eventCategory: 'Legitimation',
      eventAction: 'Is returning customer',
      nonInteraction: true
  });
  </code></pre>
  
  <p>But I don't know when GA has loaded since GTM makes everything async.
  How can I know when ga() is ready?</p>