title: Javascript - event.clientX & style.left - Mathematical Operations
body: <p>I am stuck with a lil' problem over here. Let me explain: </p>
  
  <p><code>document.getElementById(" ... ").style.left</code> (horizontal position of object) will return a value like this: <code>100px</code> or <code>1129px</code>.</p>
  
  <p><code>event.clientX</code> (horizontal position of mouse-pointer) will return a value like this: <code>100</code>or <code>1337</code>. </p>
  
  <p>I want to make math happen between these two. For example: <code>var x = ( document.getElementById(" ... ").style.left ) + (event.clientX )</code></p>
  
  <p>How can I do this, when one returns a value with <code>px</code>and the other without? How can I get a regular number/px-number out of this? It does not seem to work to just add a <code>(event.clientX) + "px"</code> or <code>document.getElementById(" ... ").style.left - "px"</code></p>
  
  <p>Best regards! Comment if something is unclear I suppose!  </p>