Calculate

index.js

function calculateAverageBaseRate(
    leaseTerm,
    baseRate,
    escalationValue,
    escalationType,
    freeRentType,
    opex,
    sizeSf,
    numOfFreeMonths,
  ) {
    // variables
    let averageBaseRate = 0

    // early return due to free duration
    if (leaseTerm <= numOfFreeMonths) {
        return 0;
    }

    // helper utils
    let round2digits = (num) => (Math.round(num * 100)) / 100;
    let accumulateBaseRate = escalationValue => rate => rate + rate * escalationValue / 100;
  
    // in between a year
    if (numOfFreeMonths < leaseTerm && leaseTerm <= numOfFreeMonths + 11) {
        return round2digits((baseRate * (leaseTerm - numOfFreeMonths)) / leaseTerm);
    }

    // accumulator for base rate during yearly interval
    let accumulatorBaseRate = accumulateBaseRate(escalationValue);

    // over a year accumulation
    // TODO: numberOfFreeMonths bigger than 12
    let totalBaseRent = 0
    let totalBaseRentFirstYear = 0
    let monthsToCalculate = 0
    let shouldStartPeriod = false
    
    if (numOfFreeMonths <= 12) {
        totalBaseRentFirstYear = (baseRate / 12) * sizeSf * (12 - numOfFreeMonths);
        monthsToCalculate = leaseTerm - 12;
        shouldStartPeriod = true;
        // console.log('totalBaseRentFirstYear = ' + totalBaseRentFirstYear)
    } else {
        totalBaseRentFirstYear = 0;
        monthsToCalculate = leaseTerm - numOfFreeMonths;
        shouldStartPeriod = false;
    }
    // console.log('monthsToCalculate = ' + monthsToCalculate)
    
    totalBaseRent = totalBaseRentFirstYear; // initial value for first fiscal year

    let accBaseRate = 0 // accumulator for base rate
    // next calculation is less than a year
    if (monthsToCalculate <= 12) {
        // this time, base rate is accumulated
        accBaseRate = !shouldStartPeriod ? baseRate : baseRate + baseRate * escalationValue / 100;
        // console.log(accBaseRate)
        totalBaseRent += ( (accBaseRate/12) * sizeSf * monthsToCalculate );
    } 
    // make interval calculation
    else {
        let intervalYear = parseInt(monthsToCalculate / 12);
        let remainMonths = monthsToCalculate - (12 * intervalYear);
        // console.log('intervalYear = ' + intervalYear)
        // console.log('remainMonths = ' + remainMonths)
        // console.log('shouldStartPeriod = ' + (shouldStartPeriod))

        // initial accumulate value of base rate
        accBaseRate = baseRate
        for (let i = 0; i < Math.round(intervalYear); i++) {
            if (!shouldStartPeriod) {
                shouldStartPeriod = true
            } else {
                accBaseRate = (accumulatorBaseRate(accBaseRate))
            }
            totalBaseRent += (accBaseRate * sizeSf);
            // console.log('accBaseRate = ' + accBaseRate + ' | totalRent = ' + (accBaseRate * sizeSf))
        }
        if (remainMonths > 0) {
            accBaseRate = (accumulatorBaseRate(accBaseRate))
            totalBaseRent += ((accBaseRate / 12) * sizeSf * remainMonths);
            // console.log('accBaseRate = ' + accBaseRate + ' | totalRent = ' + ((accBaseRate / 12) * sizeSf * remainMonths))
        }
    }
    // console.log('totalBaseRent = ' + totalBaseRent)

    // calculate average base rate
    averageBaseRate = ((totalBaseRent / leaseTerm) / sizeSf) * 12;
  
    // round up to 2 decimal digits
    // return parseFloat(averageBaseRate.toFixed(2));
    return round2digits(averageBaseRate)
}


////////////////////////////////
// TESTING
////////////////////////////////
function test(expect, actual) {
    if (expect === actual) {
        console.log('[OKAY] ' + expect + ' = ' + actual)
    } else {
        console.log('DAMN IT -_-; ---> ' + expect + ' != ' + actual)
    }
}

/// free months = 4
test(0,     calculateAverageBaseRate(4,  13.50, 3, 'Percent', 'Base', 4.32, 25245, 4))
test(2.7,   calculateAverageBaseRate(5,  13.50, 3, 'Percent', 'Base', 4.32, 25245, 4))
test(9,     calculateAverageBaseRate(12, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 4))
test(9.9,   calculateAverageBaseRate(15, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 4))
test(10.23, calculateAverageBaseRate(16, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 4))
test(11.45, calculateAverageBaseRate(24, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 4))
test(11.57, calculateAverageBaseRate(25, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 4))
test(11.67, calculateAverageBaseRate(26, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 4))
test(13.27, calculateAverageBaseRate(55, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 4))

/// free months = 12
test(1.93, calculateAverageBaseRate(14, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 12))

/// free months = 13
test(0.96, calculateAverageBaseRate(14, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 13))
test(1.80, calculateAverageBaseRate(15, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 13))
test(6.19, calculateAverageBaseRate(24, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 13))
test(6.48, calculateAverageBaseRate(25, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 13))
test(8.10, calculateAverageBaseRate(32, 13.50, 3, 'Percent', 'Base', 4.32, 25245, 13))