SpreadJS Evaluate Formula

HTML

<div id="ss"></div>
    <input type="button" id="button1" value=" First scroll and then Freeze Rows" onclick="freezeRows()" />
<script type="text/javascript">
        
        function freezeRows() {
            var spread = $("#ss").wijspread("spread");
            var activeSheet = spread.getActiveSheet();
            var topRow = activeSheet.getViewportTopRow(1);
            activeSheet.isPaintSuspended(true);
            for (var i = 0; i < topRow; i++) {
                activeSheet.setRowVisible(i, false);
            }
            activeSheet.setFrozenRowCount(topRow + 1);
            activeSheet.isPaintSuspended(false);

        }
    </script>

JavaScript

$("#ss").wijspread();

            var spread = $("#ss").wijspread("spread");
            var activeSheet = spread.getActiveSheet();
            activeSheet.setRowCount(20);
            activeSheet.setColumnCount(20);
activeSheet.isPaintSuspended(true);
            for (var i = 0; i < 5; i++) {
                activeSheet.setRowVisible(i, false);
                activeSheet.setColumnVisible(i, false);
            }
activeSheet.isPaintSuspended(false);