Javascript to compare dates

[itsmyworld]

Hi,

I am using the following javascript (taken from one of the posts here) to compare from and two dates.
Javascript is places to the right of finish button.
Two parameters are par_fromdate and par_todate.
I am using two edit box date prompts.

Its not prompting error for from date  > to date.
Can you please help me to figureout the error.

Thanks

<script type="text/javascript">
var cntlName;
function right(str, n)
{
   if (n <= 0)
     {   
       return "";
     }
   else if (n > String(str).length)
     {
       return str;
     }
   else
     {
        var iLen = String(str).length;
        return String(str).substring(iLen, iLen - n);
     }
}

function customCheckPage()
{
   var par1;
   var par2;
   for( var i=0; i<preProcessControlArray.length; i++)
     {
        cntlName = eval(preProcessControlArray);
     if (cntlName.m_oSubmit.name.toLowerCase() == 'par_fromdate' )
           {
          eval('pickerControl' + cntlName.m_sRef + '.lostFocus()');
          par1 = cntlName.m_oForm.value;
           }   
     if (cntlName.m_oSubmit.name.toLowerCase() == 'par_todate' )
           {
          eval('pickerControl' + cntlName.m_sRef + '.lostFocus()');
          par2 = cntlName.m_oForm.value;
        }
     }

   if (par1<=par2)
      {
    //alert ('CORRECT');   
     promptButtonFinish();
      }
   else
      {
     alert('FROM DATE parameter must be smaller than or equal to TO DATE parameter!');
      }

   for( var i=0; i<pageNavigationObserverArray.length; i++)
      {
     cntlName = eval( pageNavigationObserverArray );
     if(cntlName.m_oParent.onclick.toString().indexOf('promptButtonFinish()')>0 )
           {
          cntlName.m_oParent.onclick = customCheckPage;
        }
      }
   for( var i=0; i<preProcessControlArray.length; i++)
      {
     cntlName = eval(preProcessControlArray);
     dt = new Date();
     df = new Date( dt - 30*86400000);
     if (cntlName.m_oSubmit.name.toLowerCase() == 'par_fromdate' )
            {
          cntlName.m_oEditBox.value = df.getFullYear()
                     + '-' + right('0'+(1+df.getMonth()),2)
                     + '-' + right('0'+df.getDate(),2);
          eval('pickerControl' + cntlName.m_sRef + '.lostFocus()');
         }
     if (cntlName.m_oSubmit.name.toLowerCase() == 'par_todate' )
            {
          cntlName.m_oEditBox.value = dt.getFullYear()
                     + '-' + right('0'+(1+dt.getMonth()),2)
                     + '-' + right('0'+dt.getDate(),2);
          eval('pickerControl' + cntlName.m_sRef + '.lostFocus()');
         }
     }
}
</script>