Arr = [
    {rowIndex: 5, value: 10},
    {rowIndex: 5, value: 20},
    {rowIndex: 5, value: 30},
    {rowIndex: 6, value: 40},
    {rowIndex: 6, value: 50},
    {rowIndex: 6, value: 60},
    {rowIndex: 7, value: 70},
    {rowIndex: 7, value: 80},
    {rowIndex: 7, value: 90}]

arrNew = (['5',[10, 20, 30]], ['6',[40, 50, 60]], ['7',[70, 80, 90]])

<table>
    <tr>
        <td>10</td>
        <td>20</td>
        <td>30</td>
    </tr>
    <tr>
        <td>40</td>
        <td>50</td>
        <td>60</td>
    </tr>
    <tr>
        <td>70</td>
        <td>80</td>
        <td>90</td>
    </tr>
</table>