document.getElementById.all Not working in Chrome but works in Internet Explorer browser

<script type="text/javascript"  language="javascript">
        function check() {            var valid = false;
            var gv = document.getElementById("MainContent_abc");
            for (var i = 0; i < gv.all.length; i++) {
                var node = gv.all[i];
                if (node != null && node.type == "checkbox" && node.checked) {
                    valid = true; break;                }            }
            if (!valid) {
                alert("Select atleast one item to delete");
                return false;            }            else {
                return confirm("Are you sure you want to delete?");            }
        }    </script>