title: Onmouseover change CSS class from other element
body: <p>I'm trying to make an JS, but since I'm not an expert on that, maybe someone could help me. I was searching for that in Google and in Stack Overflow, but didn't find what I need. I just found <code>onmouseover</code> that change the class in element itself. But I want something different:</p>
  
  <p>I want to make a <code>onmouseover</code> on <code>a</code> tag to change the class <code>closed</code> to <code>open</code> in other element. Example:</p>
  
  <p><code>&lt;a href="#" onmouseover="&lt;active event&gt;"&gt;Link&lt;/a&gt;</code></p>
  
  <p><code>&lt;ul class="dropdown closed"&gt;&lt;li&gt;Item&lt;/li&gt;&lt;/ul&gt;</code></p>
  
  <p>Regards,</p>