Calculation Steps
No calculations yet.
function calculateAutoLoan() {
const loanAmount = parseFloat(document.getElementById(“loanAmount”).value);
const loanTerm = parseInt(document.getElementById(“loanTerm”).value);
const interestRate = parseFloat(document.getElementById(“interestRate”).value) / 100;
if (isNaN(loanAmount) || isNaN(loanTerm) || isNaN(interestRate) || loanAmount <= 0 || loanTerm <= 0 || interestRate <= 0) {
alert("Please enter valid positive values for all fields.");
return;
}
const numberOfPayments = loanTerm * 12;
const monthlyInterestRate = interestRate / 12;
const discountFactor = (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1) / (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments));
const monthlyPayment = loanAmount / discountFactor;
const totalAmount = monthlyPayment * numberOfPayments;
const totalInterest = totalAmount – loanAmount;
document.getElementById("monthlyPayment").value = monthlyPayment.toFixed(2);
document.getElementById("totalInterest").value = totalInterest.toFixed(2);
document.getElementById("totalAmount").value = totalAmount.toFixed(2);
displayCalculationSteps(loanAmount, loanTerm, interestRate, monthlyPayment, totalInterest, totalAmount);
}
function displayCalculationSteps(loanAmount, loanTerm, interestRate, monthlyPayment, totalInterest, totalAmount) {
const stepsDetails = `
Inputs:
Loan Amount: $${loanAmount.toFixed(2)}
Loan Term: ${loanTerm} years
Interest Rate (APR): ${interestRate * 100}%
Formulas:
Monthly Payment = Loan Amount ÷ Discount Factor
Discount Factor = ( (1 + Monthly Interest Rate) ^ Number of Payments – 1 ) ÷ (Monthly Interest Rate * (1 + Monthly Interest Rate) ^ Number of Payments)
Results:
Estimated Monthly Payment: $${monthlyPayment.toFixed(2)}
Total Interest: $${totalInterest.toFixed(2)}
Total Loan Amount: $${totalAmount.toFixed(2)}
`;
document.getElementById(“stepsDetails”).innerHTML = stepsDetails;
document.getElementById(“calculationSteps”).style.display = “block”;
}
function resetAutoLoan() {
document.getElementById(“autoLoanCalculatorForm”).reset();
document.getElementById(“monthlyPayment”).value = “”;
document.getElementById(“totalInterest”).value = “”;
document.getElementById(“totalAmount”).value = “”;
document.getElementById(“calculationSteps”).style.display = “none”;
}
