title: Execute fadeIn callback only once
body: <p>I did this small example to simulate my problem:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>$(document).ready(function(){
    var callback = function(){
      output.innerHTML += '&lt;br&gt;Fade example finished !!';
    };
    $('.fade').fadeOut('fast').fadeIn(callback);
  });</code></pre>
  <pre class="snippet-code-css lang-css prettyprint-override"><code>div {
    display: block;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"&gt;&lt;/script&gt;
  
  &lt;div class="fade"&gt;Fade example&lt;/div&gt;
  &lt;div class="fade"&gt;Fade example&lt;/div&gt;
  &lt;div class="fade"&gt;Fade example&lt;/div&gt;
  &lt;div id="output"&gt;Output: &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>As you can see, the fadeIn callback executes once per div.</p>
  
  <p>However I want it to run only once for all <code>'.fade'</code> elements.</p>
  
  <p>Is there any property I can set, so the callback is executed only once?</p>