[ruslan_mart]

<div class="CatalogList">
  <div>
    <img src="img1.jpg">
    <div class="button">11</div>
  </div>
  <div>
    <img src="img2.jpg">
    <div class="button">22</div>
  </div>
  <div>
    <img src="img3.jpg">
    <div class="button">33</div>
  </div>
</div>

<script>
function catalog()
{
   var a = 'getElementsBy';
   for(i=0;i<3;i++)
   {
      eval('document.'+a+'ClassName(\'button\')['+i+']').onclick = function()
      {
         alert( eval('this.parentNode.'+a+'TagName(\'img\')[0].src') );
      }
   }
}
catalog();
</script>