title: Adding css property value to existing value with javascript
body: <p>I'm trying to change ul translate with JS </p>
  
  <pre><code>&lt;ul id="navigation" style="-webkit-transform: translateX(0px);"&gt;&lt;/ul&gt;
  </code></pre>
  
  <p>by clicking on button</p>
  
  <pre><code>&lt;input type="button" value="&gt;" onclick="pomakDesno()" class="button"/&gt;  
  </code></pre>
  
  <p>But when I change it using onclick I would like with every click to increase it, in otherwords, add some value to already existing value. I have this code. What am I doing wrong? </p>
  
  <pre><code>    &lt;script&gt;
          function pomakDesno(){
          var mvalue=document.getElementById('navigation').style.WebkitTransform;
          var tvalue=111;
          var zvalue= mvalue+tvalue;
          document.getElementById('navigation').style.WebkitTransform='translateX(' + zvalue + 'px)';}
  
      &lt;/script&gt;
  </code></pre>