this.getElementCount = function(doc, type, pattern, attr) {
        var inputPar = type.split(";");
        var allRequestedElementCount =  0 ;
        var reg = new RegExp(pattern);
        for (var i =  0 ; i < doc.forms.length; i++) {
            for (var j =  0 ; j < doc.forms.elements.length; j++) {
                for (var k =  0 ; k < inputPar.length; k++) {
                    if (doc.forms[i].elements[j].type == inputPar[k] && reg.exec(doc.forms[i].elements[j].getAttribute(attr))) {
                        allRequestedElementCount++;
                    }
                }
            }
        }

 protected void Page_Load(object sender, EventArgs e)
        {
            Button1.Attributes.Add("onclick", string.Format("Prices()"));
        }

 <script>
function Prices()
{
      window.showModalDialog('Prices.htm', '', 'dialogWidth: 820 px;dialogHeight: 600  px;scrollbars=yes;center=yes;border=thin;help=no;status=no;resizable=yes');
			}
	</script>

doc.forms[i].elements[j].getAttribute(attr))