SO fiddle

Test Fiddle mainly for SO Questions

by Nick Craver

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/overcast/jquery-ui.css">
 <select id="dropdown" class="boxformwh" name="dropdown"> 
    <option style="margin:20px;" value="area1"><b>DIV Area 1</b></option> 
    <option style="margin:20px;" value="area2"><b>DIV Area 2</b></option> 
    <option style="margin:20px;" value="area3"><b>DIV Area 3</b></option> 
 </select> 


  <div>
    <div id="divarea1" class="box">DIV Area 1</div> 
    <div id="divarea2" class="box">DIV Area 2</div> 
    <div id="divarea3" class="box">DIV Area 3</div> 
  </div>

JavaScript

$(document).ready(function() {
     $('.box').hide();
     $('#dropdown').change(function() {
         $('.box').hide();
         $('#div' + $(this).val()).show();
     }).change();
 });