https://www.codewars.com/kata/buying-a-car/train/javascript

BuyACar.js

function nbMonths(startPriceOld, startPriceNew, savingperMonth, percentLossByMonth) {
  //your code here
  if (startPriceOld >= startPriceNew) {
    return [0, Math.floor(startPriceOld - startPriceNew)];
  }
  
  let months = 0;
  let totalSaving = 0;
  let depreciatedPriceNew = startPriceNew;
  let depreciatedPriceOld = startPriceOld;
  let lossPercentage = percentLossByMonth; 
  while ((totalSaving + depreciatedPriceOld) < depreciatedPriceNew) {
    months += 1;
    if (months % 2 === 0) {
      lossPercentage += 0.5; 
    }
    totalSaving += savingperMonth;
    depreciatedPriceOld -= depreciatedPriceOld * (lossPercentage / 100);
    depreciatedPriceNew -= depreciatedPriceNew * (lossPercentage / 100);
  }
  return [months, Math.round(totalSaving + depreciatedPriceOld - depreciatedPriceNew)];
}