How can we retrieve the ID of a user created Cart within a Theme App Extension?

[triplesingle]

For more background, I want to update a Cart Attribute within my Theme App Extension with a GraphQL Mutation. This Mutation accepts the Cart ID as a param but I'm not sure how to get the cart ID of current user.

[Huptech-Web]

Hello @triplesingle 

You can get the Current user Cart ID in the theme extension by shopify cookies for that use the code below.

// 1. function for getting cookies value
const getCookie = cname => {
  var name = cname + "=";
  var ca = document.cookie.split(';');
  for (var i = 0; i < ca.length; i++) {
    var c = ca[i];
    while (c.charAt(0) == ' ') {
      c = c.substring(1);
    }
    if (c.indexOf(name) == 0) {
      return c.substring(name.length, c.length);
    }
  }
  return "";
};
// 2. Get the current user cart ID 
const cartID=getCookie("cart")?`gid://shopify/Cart/${getCookie("cart")}`:""

You get cartId = gid://shopify/Cart/Z2NwLXVzLWVhc3QxOjAxSFhSODRYMERHNVo3WlRQMVI1UUZLMU45 (for example )

use this ID in your graphQl Mutition or query 

If the solution presented meets your needs and addresses your query effectively, I encourage you to accept it as the chosen answer. This will acknowledge the support you received and aid fellow community members in identifying reliable and effective solutions for their similar concerns.
Thank you.