title: jQuery how to add a class to an element one by one with a small delay?
body: <p>jQuery how to add a class to an element one by one with a small delay when click on the #button ?
  not to add the class at once for all element.I want to do it one by one. Please help. Thanks in advance.</p>
  
  <pre><code>&lt;ul id="scroll-set"&gt;
  &lt;li class="  imVisible"&gt;Brentwood&lt;/li&gt;
  &lt;li class="imVisible "&gt;Antioch&lt;/li&gt;
  &lt;li class=" imVisible"&gt;Pittsburg&lt;/li&gt;
  &lt;li class=" imVisible"&gt;Concord&lt;/li&gt;
  &lt;li class="imVisible "&gt;Walnut Creek&lt;/li&gt;
  &lt;li class=" imVisible"&gt;Danville&lt;/li&gt;
  &lt;li class=" imVisible"&gt;San Ramon&lt;/li&gt;
  
  &lt;/ul&gt;
  &lt;div id="button"&gt;
  </code></pre>