javascript清除内容

<script type="text/javascript">
        function cleartext() {
            for (i = 0; i < window.document.forms[0].elements.length; i++) {
                if (window.document.forms[0].elements[i].type == "text") {
                    window.document.forms[0].elements[i].value = "";
                }
            }
            document.getElementById("<%= contactdescription.ClientID %>").value = "";
        }
    </script>