Answer:
function computePayment(principal, annualRate, periodsPerYear){
var pay;
pay = (principal * annualRate)/(1-(1+annualRate)-periodsPerYear);
return pay;
}
function computeBalance(principal, annualRate, periodsPerYear, numberOfPaymentsPaidToDate){
var balance ;
let num = (principal*(1+annualRate)*periodsPerYear);
let denum = numberOfPaymentsPaidToDate *((1+annualRate) * periodsPerYear-1)*annualRate;
balance = num-denum;
return balance;
}
function doPayment(){
let loanAmount = document.getElementById("principal").value;
let rate = document.getElementById("rate").value;
let duration = document.getElementsById("time").value;
let result = computePayment(loanAmount, rate, duration);
document.getElementsById("periodPay").value = result;
}
function doBalance(){
let loanAmount = document.getElementById("principal").value;
let rate = document.getElementById("rate").value;
let duration = document.getElementById("time").value;
let currentPaid = document.getElementById("paidMonths").value;
let result = computeBalance(loanAmount, rate, duration, currentPaid);
document.getElementById("displayBalance").value = result;
}
Explanation:
The javascript source code defines four functions. The 'doPayment' and 'doBalance' functions are initiated with the onclick properties of the HTML file buttons of the loan calculator. The doPayment function gets the user input from the HTML file and assigns them to variable which are used as the parameters of the computePayment function called.
The doBalance function also retrieve user input from the HTML file and calls the computeBalance function to calculate and return the balance of the loan to be paid.
