Change le style d une class javascript

<div class="classe1 classe2style1"></div>

<div class="classe1 classe2style2"></div>

<script type="text/javascript">
document.getElementsByClassName = function(classParam) {
   var retnode = [];
   var myclass = new RegExp('\\b'+classParam+'\\b');
   var elem = this.getElementsByTagName('*');
   for (var i = 0; i < elem.length; i++) {
      var classes = elem[i].className;
      if (myclass.test(classes)) retnode.push(elem[i]);
   }
   return retnode;
}; 
</script>

var elements = document.getElementsByClassName("maclasse");
for (var i=0 ; i<elements.length ; i++){
   elements[i].style.display = "none";
}