Retrieve Integer from mixed Javascript array

//Global Vars
    var button = document.getElementsByTagName('button')[0];
    var form2 = document.getElementById('form2');
    var form3 = document.getElementById('form3');
    var tax = 0.0875;
    var orderText;
    var subtotal;
    var total;
    var orderArray = [];
    var n = 1;

    //Form Button
    button.addEventListener("click", function(){

        //Local Selection Vars
        var sizeChecked = document.querySelector('input[name="size"]:checked');
        var crustChecked = document.querySelector('input[name="crust"]:checked');
        var toppingsChecked = document.querySelector('input[name="toppings"]:checked');
        var breadsticksChecked = document.querySelector('input[name="breadsticks"]:checked');

        //Adding Cost
        subtotal = parseInt(sizeChecked.value) + parseInt(crustChecked.value) + parseInt(toppingsChecked.value) + parseInt(breadsticksChecked.value);
        total = Math.round((subtotal + (subtotal * tax)) * 100) / 100;

        //Container Var for Selected Menu Items
        orderText = sizeChecked.getAttribute('data-size')+' '+ crustChecked.getAttribute('data-crust')+' crust pizza topped with ' +
                    toppingsChecked.getAttribute('data-toppings')+' '+breadsticksChecked.getAttribute('data-breadsticks');

        //Pushing Cost and Selected Items to Array
        orderArray.push('<p>Order '+n+': $'+subtotal+'</p>');
        orderArray.push('<p>One '+orderText+'.</p>');
        orderArray.toString();

        //Form2 HTML template with order array
        form2.innerHTML = '<p class="underline textcenter">Order</p>'+'<p>'+orderArray+'</p>'+'<br><button id="buttonCheckout">Add to Cart</button>';

        //Updating Order Number for next order
        n++;

        //Local Button Vars
        var button2 = document.getElementById('buttonCheckout');
        var button3 = document.getElementById('buttonPay');

        //Form2 Button
        button2.addEventListener("click", function(){

        console.log('button2 click');
        form3.innerHTML = '<p class="underline textcenter">Pay</p><p>Subtotal: $'+subtotal+'</p><p>Tax: $'+(subtotal * tax)+
                          '</p><p>Total: $'+total+'</p><br><button id="buttonPay">Make Payment</button>';

        });

    });