js实现手机号码和身份证号码校验

<script type="text/javascript">
        function checkform() {
            
            var re;
            var ss = document.getElementById('txtMobile').value;
            re = /^(1[358][0-9]{9})$/;
            if (re.test(ss)==false) {
                alert("手机号码输入不合法");
                return false; 
            }

            var id=document.getElementById("txtIDNUMBER").value;
            var reg = /(^\d{15}$)|(^\d{18}$)|(^\d{17}(\d|X|x)$)/;
            if (reg.test(id) === false) {
                alert("身份证输入不合法");
                return false;
             }
               
        }
    </script>