Google Apps Script column format

I just set up a script to automatically calculate the duration of shifts as they're submitted from a Google Form and transferred to a linked Google Sheet. The duration keeps formatting as hh:mm:ss AM/PM and I want it to format up as hh:mm (no AM/PM) without messing up the current code or having to constantly change it via the number format tab in Google Sheets. Help?

Current code is:

function FillFormulas() {
  var spreadsheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Responses');
  var lastRow = spreadsheet.getLastRow();
  spreadsheet.getRange("F2").setFormula("=E2-D2");
  var fillDownRange = spreadsheet.getRange(2, 6, (lastRow - 1)); 
  spreadsheet.getRange("F2").copyTo(fillDownRange);
}

I tried multiple different things, don't quite remember what, but none of them worked. The code kept getting messed up.

Although I'm not sure whether I could correctly understand your expected result, how about the following modification?

From:

var fillDownRange = spreadsheet.getRange(2, 6, (lastRow - 1)); 

To:

var fillDownRange = spreadsheet.getRange(2, 6, (lastRow - 1)).setNumberFormat('hh:mm'); // or 'hh":"mm'

Reference:

• setNumberFormat(numberFormat)

I hope this is what you want and it works for you.

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function FillFormulas() {
  var spreadsheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Responses');
  var lastRow = spreadsheet.getLastRow();
  spreadsheet.getRange("F2").setFormula("=E2-D2");
  var fillDownRange = spreadsheet.getRange(2, 6, (lastRow - 1)); 
  spreadsheet.getRange("F2").copyTo(fillDownRange);

  var durationFormat = "hh:mm"; // Desired duration format (hh:mm)

  // Format duration in the range fillDownRange
  fillDownRange.setNumberFormat(durationFormat);
}

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