Combining a loop function and IF condition in google app scirpt

New to google app script and trying to create a function which combines loop (can be map, for or forEach) and IF condition.

See public spreadsheet for data: https://docs.google.com/spreadsheets/d/1V7CpCxBH0lg6wi1TAhfZJP5gXE8hj7ivQ8_ULxLSLgs/edit?usp=sharing

I wish to create an array inside a variable. In this array I want all quantity of column "D" but only if column "C" is "Buy".

This is the code I have tried but it comes back empty:

const ss = SpreadsheetApp.getActiveSpreadsheet();
    const historySheet = ss.getSheetByName('Blad1');

function quantBuy () {
  const searchRange = historySheet.getRange(3,2,historySheet.getLastRow()-1, 2)
  let rangeValues = searchRange.getValues();
  for (i = 0; i < historySheet.getLastRow()-1; i++) {
    if (rangeValues[i] === 'Buy') {
      console.log(i);
  }}}

Any help is appreciated.