//Get values from form
                            function getValues(){
                                let principleAmt = document.getElementById("loanAmt").value;
                                let termsOfLoan = document.getElementById("numMonths").value;
                                let interestRate = document.getElementById("interest").value;
                            
                                let principle = parseFloat(principleAmt);
                                let terms = parseInt(termsOfLoan);
                                let interest = parseFloat(interestRate);
                            
                                if (Number.isInteger(principle) && Number.isInteger(terms) && Number.isInteger(interest))
                                {
                                    let monthlyPayment = calculateMonthlyPayment(principle, terms, interest);
                                    let totalCostOfLoan =  calculateTotalCostOfLoan(monthlyPayment, terms);
                                    let totalInterest = calculateTotalInterst(principle, totalCostOfLoan);
                            
                                    displayLoanDetails(monthlyPayment, principle, totalInterest, totalCostOfLoan);
                                    displayAmortizationTable(principle, monthlyPayment, terms, interest);
                                } else {
                                    alert("You must enter a valid number!! Please try again!!");
                                }
                            
                            }
                            
                            
                            //Calculate Total Monthly Payments
                            function calculateMonthlyPayment(principle, terms, interest){
                                let paymentMultiplier = ((interest / 1200)/(1 - ((1 + interest / 1200) ** (terms * -1))));
                                return principle * paymentMultiplier;
                            }
                            
                            //Calculate Total Interest 
                            function calculateTotalCostOfLoan(monthlyPayment, terms){
                                let totalCost = monthlyPayment * terms;
                                return totalCost;
                            }
                            
                            //Calculate Total Cost of Loan
                            function calculateTotalInterst(principle, totalCostOfLoan){
                                let totalInterest = totalCostOfLoan - principle;
                                return totalInterest;
                            }
                            
                            
                            //Display Calc'd values
                            function displayLoanDetails(monthlyPayment, principle, totalInterest, totalCost){
                                let monthlyPaymentDisplay = `${monthlyPayment.toFixed(2)}`;
                                let totalPrincipalDisplay = `${principle.toFixed(2)}`;
                                let totalInterestDisplay = `${totalInterest.toFixed(2)}`;
                                let totalCostDisplay = `${totalCost.toFixed(2)}`;
                            
                                document.getElementById("monthlyPayment").innerHTML = monthlyPaymentDisplay;
                                document.getElementById("totalPrincipal").innerHTML = totalPrincipalDisplay;
                                document.getElementById("totalInterest").innerHTML = totalInterestDisplay;
                                document.getElementById("totalCost").innerHTML = totalCostDisplay;
                            }
                            
                            //display amortization Table
                            function displayAmortizationTable(principle, monthlyPayment, terms, interest){
                                let newBalance = principle;
                                let totalInterest = 0;
                                let tablebody = document.getElementById("results");
                                let templateRow = document.getElementById("amortTemplate");
                            
                                tablebody.innerHTML = "";
                            
                                for(let i = 1; i <= terms; i++){
                                    let tableRow = document.importNode(templateRow.content, true);
                            
                                    let interestPayment = newBalance * (interest/1200);
                                    totalInterest += interestPayment;
                                    let principalPayment = monthlyPayment - interestPayment;
                                    newBalance = newBalance - principalPayment;
                                 
                                    //grab number of tds and put into an array
                                    let rowCols = tableRow.querySelectorAll("td");
                                    rowCols[0].classList.add(i);
                                    rowCols[0].textContent = i;
                            
                                    rowCols[1].classList.add(monthlyPayment);
                                    rowCols[1].textContent = monthlyPayment.toFixed(2);
                            
                                    rowCols[2].classList.add(principalPayment);
                                    rowCols[2].textContent = principalPayment.toFixed(2);
                            
                                    rowCols[3].classList.add(interestPayment);
                                    rowCols[3].textContent = interestPayment.toFixed(2);
                            
                                    rowCols[4].classList.add(totalInterest);
                                    rowCols[4].textContent = totalInterest.toFixed(2);
                            
                                    rowCols[5].classList.add(newBalance);
                                    rowCols[5].textContent = newBalance.toFixed(2);
                            
                                    tablebody.appendChild(tableRow);
                                }
                            }
                            
                        

The code is structured into six functions.

getValues

getValues retrieves the values entered and sends them to be calculated, then displayed into an amortization table.

calculateMonthlyPayment

calculateMonthlyPayment calculates the monthly payment for the loan based on the terms and interest rate.

calculateTotalCostOfLoan

calculateTotalCostOfLoan is calculated by mutiplying the monthly payment by the terms, or number of months of payment.

calculateTotalInterest

calculateTotalInterest is calculated here by subtracting the principal from the total cost of the loan.

displayLoanDetails

displayLoanDetails deiplays the monthly payment, principal loan amount, total interest of loan, and the total cost of loan.

displayAmortizationTable

displayAmortizationTable displays the monthly payments into a table. Each row, or month, will show monthly payment, principal payment, interest payment, total interest paid, and new balance of the loan.