How to Build a Real Estate Calculator

function analyzeRealEstateInvestment(price, downPayment, monthlyRent, expenses, loanRate, loanYears) {
  const loan = price - downPayment;
  const monthlyMortgage = calculateMortgagePayment(loan, loanRate, loanYears);
  const annualDebtService = monthlyMortgage * 12;

  const grossRent = monthlyRent * 12;
  const annualExpenses = expenses.taxes + expenses.insurance + expenses.maintenance + expenses.vacancy;
  const noi = grossRent - annualExpenses;
  const cashFlow = noi - annualDebtService;

  return {
    capRate: (noi / price) * 100,
    cashOnCash: (cashFlow / downPayment) * 100,
    monthlyCashFlow: cashFlow / 12,
    noi,
    debtService: annualDebtService
  };
}