Returns a number from 1 to 7 identifying the day of the week of a date..
| Name | Type | Description |
| arg1 | number | Is a number that represents a date. |
| arg2 | number | Is a number: for Sunday=1 through Saturday=7, use 1; for Monday=1 through Sunday=7, use 2; for Monday=0 through Sunday=6, use 3. |
builder.CreateFile("xlsx");
const oWorksheet = Api.GetActiveSheet();
var oFunction = Api.GetWorksheetFunction();
var ans = oFunction.WEEKDAY("11/5/2018", 2);
oWorksheet.GetRange("C1").SetValue(ans);
builder.SaveFile("xlsx", "WEEKDAY.xlsx");
builder.CloseFile();