Edit in JSFiddle 

ko.applyBindings({colors: ['red', 'yellow', 'green']});

<!DOCTYPE html>
<html ng-app>
    <head>
        <title>Rowspan Demo</title>
    </head>
    <body>
        <table border="1">
            <tbody data-bind="foreach: colors">
                <tr>
                    <!-- ko if: $index() == 0 -->
                    <td data-bind="attr:{rowspan : $parent.colors.length}">Colors</td>
                    <!-- /ko -->
                    <td data-bind="text: $data"></td>
                </tr>
            </tbody>
        </table>
    </body>
</html>

              

              

              

                
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