title: Count number of Divs filtering on id/class
body: <p>Hiii,<br>
  <strong>Q-></strong>
  I want to count the number of <code>div</code> in a page whose id start with d  </p>
  
  <pre><code>&lt;div id="d1"&gt;D1&lt;/div&gt;
  &lt;div id="d2"&gt;D2&lt;/div&gt;
  &lt;div id="d3"&gt;D3&lt;/div&gt;
  </code></pre>
  
  <p>I want to get 3 here</p>
  
  <hr>
  
  <p><strong>Q-></strong>
  I want to count the number of <code>div</code> in a page which have the class d  </p>
  
  <pre><code>&lt;div class="d"&gt;D1&lt;/div&gt;
  &lt;div class="d"&gt;D2&lt;/div&gt;
  </code></pre>
  
  <p>I want to get 2 here</p>