How to add second product to cart in Shopify from product page - shopify

Question

I'm using Shopify and am trying to add the options to add gift wrap and a carry case to products being bought.
I can use the item.properties to ask the user for the choice and show that in the cart.
I now want to add an additional product to the cart if item.properties is set to "gift wrap" or "carry case".
This code is placed in the product-template.liquid but does not work:
{% for property in item.properties %}
{% if property.last == "Gift Wrap" %}
<p>This would add gift wrap.</p>
<script>
jQuery.post('/cart/update.js', {
updates: {
32005672697928: 1
}
});
</script>
{% endif %}
{% if property.last == "Carry Strap" %}
<p>This would add carry strap.</p>
{% endif %}
{% endfor %}
{% endunless %}

Answer 1

Doesn't seem the code you have was intended to be used on the product page. It looks like it should be placed on the cart page within the {% for item in cart.items %} ... {% endfor %} loop.
Also, this code will add only 1 wrap product, even if customers add 2+ wrapped items. I would change the code to something like the below:
{%- assign numWrappedItems = 0 -%}
{%- for item in cart.items -%}
{%- for property in item.properties -%}
{%- if property.last == "Gift Wrap" -%}
{%- assign numWrappedItems = numWrappedItems | plus: item.quantity -%}
{%- break -%}
{%- endif -%}
{%- endfor -%}
...
{%- endfor -%}
{%- if numWrappedItems > 0 -%}
<script>
jQuery.post('/cart/update.js', {
updates: {
32005672697928: {{ numWrappedItems }}
}
});
</script>
I hope the above makes sense.