js判断checkbox的全选反选

 <script language="javascript" type="text/javascript">

        function selectAll(ctlName, bool) {
            var ctl = document.getElementById(ctlName);
            var checkbox = ctl.getElementsByTagName('input');

            for (var i = 0; i < checkbox.length; i++) {
                if (checkbox[i].type == 'checkbox') {
                    checkbox[i].checked = bool;
                }
            }
        }
        function hasselect() {
            var checkbox = document.getElementsByTagName('input');
            var haschecked = false;
            for (var i = 0; i < checkbox.length; i++) {
                if (checkbox[i].type == 'checkbox') {
                    if (checkbox[i].checked) {
                        haschecked = true;

                    }
                }
            }

            if (!haschecked) {
                alert('请选择订单！');
                return false;
            }
        }
    </script>