Returns the ISO week number in the year for a given date.
| Name | Type | Description |
| arg1 | number | Is the date-time code used by Microsoft Excel for date and time calculation. |
builder.CreateFile("xlsx");
const oWorksheet = Api.GetActiveSheet();
var oFunction = Api.GetWorksheetFunction();
var ans = oFunction.ISOWEEKNUM("9/1/2017");
oWorksheet.GetRange("C1").SetValue(ans);
builder.SaveFile("xlsx", "ISOWEEKNUM.xlsx");
builder.CloseFile();