title: How to detect elements overlapping (overlaying) using JavaScript?
body: <p>How to detect overlap HTML elements, using JavaScript?</p>
  
  <p>I have an item list (<code>&lt;ul&gt;</code>). It slides up and down using JavaScript. When it slides down, depending on number of item, it may overlap the other element (<code>&lt;div&gt;</code>), which is absolute positioned at this time (it can be changed).</p>
  
  <p>How I can detect, when <code>&lt;ul&gt;</code> overlaps this <code>&lt;div&gt;</code>, to apply new style to the <code>&lt;div&gt;</code> to hide it temporary or to move it down a little bit, to prevent overlapping?<br>It's just not looking good, when they overlap))</p>
  
  <p>Here you can see, what I'm talking about: <a href="http://timetable.raj.fvds.ru/" rel="noreferrer">http://timetable.raj.fvds.ru/</a></p>
  
  <p>Thanks a lot!</p>