Amortization Loan Calculator W Extra Payments

let calcSteps = “”; const currencySymbol = “$”, fixedCurrency = “USD”; function calculateAmortization() { calcSteps = “”; const loanAmount = parseFloat(document.getElementById(“loanAmount”).value); const interestRate = parseFloat(document.getElementById(“interestRate”).value) / 100 / 12; const loanTerm = parseFloat(document.getElementById(“loanTerm”).value) * 12; const extraPayment = parseFloat(document.getElementById(“extraPayment”).value); if (isNaN(loanAmount) || isNaN(interestRate) || isNaN(loanTerm) || isNaN(extraPayment) || loanAmount <= 0 || loanTerm <= 0) { alert("Please enter valid positive values for all fields."); return; } const monthlyPayment = (loanAmount * interestRate) / (1 – Math.pow(1 + interestRate, -loanTerm)); const totalPayment = (monthlyPayment + extraPayment) * loanTerm; document.getElementById("monthlyPayment").value = formatCurrency(monthlyPayment + extraPayment); document.getElementById("totalPaid").value = formatCurrency(totalPayment); calcSteps += `Inputs:
Loan Amount: ${formatCurrency(loanAmount)}
Interest Rate: ${(interestRate * 100).toFixed(2)}%
Loan Term: ${loanTerm / 12} years
Extra Monthly Payment: ${formatCurrency(extraPayment)}

`; calcSteps += `Formulas:
Monthly Payment = Loan Amount × Interest Rate / (1 – (1 + Interest Rate) ^ -Term)
Total Paid = (Monthly Payment + Extra Payment) × Term

`; calcSteps += `Results:
Monthly Payment: ${formatCurrency(monthlyPayment + extraPayment)}
Total Paid: ${formatCurrency(totalPayment)}
`; calcSteps += `Tip: Extra payments can significantly reduce the loan’s term and total interest paid.`; if (document.getElementById(“calculationSteps”).style.display === “block”) { document.getElementById(“calculationSteps”).innerHTML = calcSteps; } } function resetCalculator() { document.querySelectorAll(“#calculator input”).forEach(el => el.value = “”); calcSteps = “”; document.getElementById(“calculationSteps”).innerHTML = “

Not calculated yet.

“; } function toggleCalculationSteps() { const s = document.getElementById(“calculationSteps”); const a = document.getElementById(“toggleArrow”); if (s.style.display === “none” || s.style.display === “”) { s.style.display = “block”; a.style.transform = “rotate(180deg)”; s.innerHTML = calcSteps || “

Not calculated yet.

“; } else { s.style.display = “none”; a.style.transform = “rotate(0deg)”; } } function formatCurrency(n) { return currencySymbol + n.toFixed(2) + ” ” + fixedCurrency; }