You're looking at the documentation for Liquid Ajax Cart v1. Go to Liquid Ajax Cart v2

data-ajax-cart-initial-state

To do its job Liquid Ajax Cart needs to know current Shopify cart state: what products are in the cart, what total price is, what discounts are applied etc. This information is stored in the cart liquid object.

The shortest way to make the cart state accessible for JavaScript code is to convert the Shopify cart object to JSON and include it to the page content within the script tag.

In order Liquid Ajax Cart to find the script tag with the cart state, it should have the data-ajax-cart-initial-state attribute.

{% comment %} Somewhere in layout/theme.liquid {% endcomment %}

<script type="application/json" data-ajax-cart-initial-state >
  {{ cart | json }}
</script>

It is highly recommended to add the mentioned code to the layout/theme.liquid file so that the initial cart state data is accessible on all pages.

If Liquid Ajax Cart doesn’t find the data-ajax-cart-initial-state script, it will make an extra Shopify Cart API request to get the cart state.


Reference