start . me .
Directory path . web , gh , editor .

HTML Document File : product-2.html 

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Product 2</title>
</head>

<body>
    <h1>Product 2</h1>
    <p>This is another great product.</p>
    <p>Price: $20</p>
    <button onclick="addToCart('Product 2', 20)">Add to Cart</button>
    <p><a href="product-1.html">View Product 1</a></p>
    <p><a href="editor.html">View Cart</a></p>

    <script>
        function addToCart(name, price) {
            const sharedData = window.parent.persistentData;
            if (!sharedData.cart) {
                sharedData.cart = [];
            }
            sharedData.cart.push({ name, price });
            alert(name + ' has been added to your cart.');
        }
    </script>
</body>

</html>