document.addEventListener('DOMContentLoaded', function () {
    const loanAmountInput = document.getElementById('loanAmount');
    const interestRateInput = document.getElementById('interestRate');
    const loanTermInput = document.getElementById('loanTerm');
    const monthlyPaymentDisplay = document.getElementById('monthlyPayment');

    function calculateMonthlyPayment() {
        const principal = parseFloat(loanAmountInput.value);
        const annualInterestRate = parseFloat(interestRateInput.value);
        const years = parseFloat(loanTermInput.value);

        if (isNaN(principal) || isNaN(annualInterestRate) || isNaN(years) || principal <= 0 || annualInterestRate <= 0 || years <= 0) {
            monthlyPaymentDisplay.textContent = '$0.00';
            return;
        }

        const monthlyInterestRate = annualInterestRate / 100 / 12;
        const numberOfPayments = years * 12;

        const numerator = monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments);
        const denominator = Math.pow(1 + monthlyInterestRate, numberOfPayments) - 1;
        const monthlyPayment = principal * (numerator / denominator);

        if (isFinite(monthlyPayment)) {
            monthlyPaymentDisplay.textContent = `$${monthlyPayment.toFixed(2)}`;
        } else {
            monthlyPaymentDisplay.textContent = '$0.00';
        }
    }

    loanAmountInput.addEventListener('input', calculateMonthlyPayment);
    interestRateInput.addEventListener('input', calculateMonthlyPayment);
    loanTermInput.addEventListener('input', calculateMonthlyPayment);

    calculateMonthlyPayment();
});