1. Add a snippet "simple-preorder-bootstrap.liquid" with code:

<script>
    // Bootstrap for Simple Preorder app
    var SimplePreorderBootstrap = {
        "page": {{ template | json }},
        "product": {
            "id": {{ product.id | json }},
            "title": {{ product.title | json }},
            "variants": [
                {% for variant in product.variants %}
                    {
                        "id": {{variant.id}},
                        "inventory_quantity": '{{variant.inventory_quantity}}',
                        "inventory_management": '{{variant.inventory_management}}',
                        "inventory_policy": '{{variant.inventory_policy}}'
                    },
                {% endfor %}
            ]
        },
        "cart": {
            "items": [
                {% for item in cart.items %}
                    {
                        "variant_id": {{item.variant.id}},
                        "product_id": {{item.product.id}},
                        "quantity": {{item.quantity}},
                        "inventory_quantity": '{{item.variant.inventory_quantity}}',
                        "inventory_management": '{{item.variant.inventory_management}}',
                        "inventory_policy": '{{item.variant.inventory_policy}}'
                    },
                {% endfor %}
            ]
        },
        //"productSelector": "#example",
        //"variantsSelector": ".example",
        //"checkoutSelector": "[name='example']",
        //"updateSelector": "",
        "debug": true,
    };
</script>

2. In the product template "product.liquid" add the code to connect the snippet:

<!-- Snippet for Simple Preorder app -->
{% include 'simple-preorder-bootstrap' %}

3. In the cart template "cart.liquid" add the code to connect the snippet:

<!-- Snippet for Simple Preorder app -->
{% include 'simple-preorder-bootstrap' %}

4. (Not mandatory) In the snippet adjust the selectors for following buttons:

• productSelector — add to cart button
• variantsSelector — list of variants
• checkoutSelector — checkout button in cart
• updateSelector — update cart button

If this does not work, please write to support@kad.systems