Possible to format cells with xlxs without using an xlxs template file?

msageryd

After some tinkering I finally managed to format datetime data so Excel will interpret them as such. The only way I can get the cells in the sheet formatted as datetime is to preformat cells in an xlxs template file and copy from this row when I insert new rows. But I'd rather not have to use a template file, since it's a pita to update this everytime I want to add or remove a column in the dataset.

{{for controlpoints}}
    {{xlsxAdd "xl/worksheets/sheet1.xml" "worksheet.sheetData[0].row"}}
    <row>
        <c t="d"><v>{{:~toIsoDate(resolvedAt)}}</v></c>
    </row>
    {{/xlsxAdd}}
{{/for}}

{{xlsxPrint}}
{{/xlsxPrint}}

function toIsoDate(d) {
    if(!d) return null;
    var date = new Date(d);
    return date.toISOString();
}