check.js

// .checked = property that determines the checked state of an
//            HTML checkbox or radio button element

const myCheckBox = document.getElementById("myCheckBox");

const visaBtn = document.getElementById("visaBtn");

const masterCardBtn = document.getElementById("masterCardBtn");

const payPalBtn = document.getElementById("payPalBtn");

const mySubmit = document.getElementById("mySubmit");

const subResult = document.getElementById("subResult");

const paymentResult = document.getElementById("paymentResult");

mySubmit.onclick = function() {
    if(myCheckBox.checked) { //gives true value
        subResult.textContent = 'You are subscribed!';
    }
    else {
        subResult.textContent = 'You are NOT subscribed!';
    }

    if(visaBtn.checked){
        paymentResult.textContent = 'You are paying with Visa';
    }
    else if(masterCardBtn.checked){
        paymentResult.textContent = 'You are paying with MasterCard';
    }
    else if(payPalBtn.checked){
        paymentResult.textContent = 'You are paying with PayPal';
    }
    else {
        paymentResult.textContent = 'You must select a payment type';
    }
}