title: How to add class to particular li?
body: <p>I have this HTML:</p>
  
  <pre><code>&lt;ul class="how-long"&gt;
      &lt;li value="1"&gt;Any&lt;/li&gt;
      &lt;li value="1"&gt;1 day&lt;/li&gt;
      &lt;li value="2"&gt;Week end&lt;/li&gt;
      &lt;li value="7"&gt;1 Week&lt;/li&gt;
      &lt;li value="14"&gt;2 Week&lt;/li&gt;
      &lt;li value="21"&gt;3 Week&lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>On document ready I want to add new class to the 4th li element.</p>
  
  <p>This is  what I tried:</p>
  
  <pre><code>$(".how-long li").slice(3).addClass('change-color');
  </code></pre>
  
  <p>If I put an alert as:</p>
  
  <pre><code>alert($(".how-long li").slice(3).html());
  </code></pre>
  
  <p>it gives me  <strong>1 week</strong> which is right, but when I addclass the class is added to all li after 4th li.</p>
  
  <p>I want to this <strong>without adding ID</strong> to each li element.
  I can hard code class in li element directly but I want to do it dynamicaly using jQuery.</p>