The Code

                           
//calculate the payment for the loan
function calcPayment(amount, rate, term) {
    return (amount * rate) / (1 - Math.pow(1 + rate, -term));
}




//calculate the interest for the current balance of the loan
function calcInterest(balance, rate) {
    return balance * rate;
}



//convert the rate to a monthly interest rate
function calcRate(rate) {
    return rate = rate / 1200;
}




function getValues() {
    let loanAmount = document.getElementById("lAmount").value;
    //months inputed from the user
    let loanTerm = document.getElementById("lTerm").value;
    let loanRate = document.getElementById("lRate").value;

    loanAmount = Number(loanAmount);
    loanTerm = parseInt(loanTerm);
    loanRate = parseFloat(loanRate);
    loanRate = calcRate(loanRate);

    //calculate
    let payment = calcPayment(loanAmount, loanRate, loanTerm);

    //returns a list of payment objects
    let payments = getPayments(loanAmount, loanRate, loanTerm, payment);

    //
    displayData(payments, loanAmount, payment); {}
}

//build the amoritization schedule
function getPayments(amount, rate, term, payment) {
    let payments = [];

    let balance = amount;
    let totalInterest = 0;
    let monthlyPrincipal = 0;
    let monthlyIntererest = 0;
    let monthlyTotalInterest = 0;

    for (let month = 1; month <= term; month++) {

        monthlyIntererest = calcInterest(balance, rate);
        totalInterest += monthlyIntererest;
        monthlyPrincipal = payment - monthlyIntererest;
        balance = Math.abs(balance - monthlyPrincipal);

        //add the details to an object
        let curPayment = {
            month: month,
            payment: payment,
            principal: monthlyPrincipal,
            interest: monthlyIntererest,
            totalInterest: totalInterest,
            balance: balance
        };

        payments.push(curPayment);

    }

    return payments;

}
//display date to the user
function displayData(payments, loanAmount, payment) {
    let tableBody = document.getElementById("scheduleBody");

    let template = document.getElementById("schedule-Template");

    //clears the table

    tableBody.innerHTML = "";

    //configure currency formatter

    let currencyFormatter = new Intl.NumberFormat('en-US', {
        style: 'currency',
        currency: "USD"
    });

    for (let index = 0; index < payments.length; index++) {

        let payRow = template.content.cloneNode(true);

        let payCols = payRow.querySelectorAll("td");

        payCols[0].textContent = payments[index].month;
        payCols[1].textContent = currencyFormatter.format(payments[index].payment.toFixed(2));
        payCols[2].textContent = currencyFormatter.format(payments[index].principal.toFixed(2));
        payCols[3].textContent = currencyFormatter.format(payments[index].interest.toFixed(2));
        payCols[4].textContent = currencyFormatter.format(payments[index].totalInterest.toFixed(2));
        payCols[5].textContent = currencyFormatter.format(payments[index].balance.toFixed(2));

        tableBody.appendChild(payRow);
    }

    //total interest is in the last row of the payments array
    let totalInterest = payments[payments.length - 1].totalInterest;

    let totalCost = Number(loanAmount) + totalInterest;

    let totalPrincipal = Number(loanAmount);

    let labelPrincipal = document.getElementById("totalPrincipal");

    labelPrincipal.innerHTML = totalPrincipal.toLocaleString("en-US", {
        style: "currency",
        currency: "USD"
    });

    let labelInterest = document.getElementById("totalInterest");
    labelInterest.innerHTML = Number(totalInterest).toLocaleString("en-US", {
        style: "currency",
        currency: "USD"
    })

    let labelPayment = document.getElementById("payment");
    labelPayment.innerHTML = Number(payment).toLocaleString("en-US", {
        style: "currency",
        currency: "USD"
    });

    let labelTotalCost = document.getElementById("totalCost");
    labelTotalCost.innerHTML = Number(totalCost).toLocaleString("en-US", {
        style: "currency",
        currency: "USD"
    });


}
                           
                       

Using Javascript and HTML, this app ask for user inputted information and maps out loan payments.