script.js

// function that will compute the amount that the user will receive by aggregating the investment amount, investment period, and interest rate.
function compute()
{
    var principal = document.getElementById("principal").value;
    var rate = document.getElementById("rate").value;
    var years = document.getElementById("years").value; 
    var interest = principal * years * rate / 100;
    var amount = parseInt(principal) + parseFloat(interest);
    var result = document.getElementById("result");
    var year = new Date().getFullYear() + parseInt(years);

    if (principal <= 0) {
        alert('Please enter a positive number!');
        document.getElementById("principal").focus();
    }
    else {
        result.innerHTML = "If you deposit $" + "<mark>" + principal + "</mark>" + ",\<br\> at an interest rate of " + "<mark>" + rate + "%" + "</mark>" + "\<br\> You will receive an amount of $" + "<mark>" + amount + "</mark>" + ",\<br\> in the year " + "<mark>" + year + "</mark>" + "\<br\>";
    }
}

// function that will update the interest rate slider when the user changes the slider value
function updateRate() { 
    var rateval = document.getElementById("rate").value; 
    document.getElementById("rate_val").innerText = rateval;
}