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

Request state

Liquid Ajax Cart keeps the information about each Shopify Cart Ajax API request in Javascript objects that are called “Request state”.

The objects usually passed as a parameter to the callbacks that you define using the Cart Ajax API requests functions.

The object looks like this:

{
  "endpoint": "/cart/add.js",
  "requestBody": {"items": [{"id": 40934235668668, "quantity": 1}], "sections": "my-cart"},
  "requestType": "add",
  "info": {
    "initiator": Element {}
  },
  "responseData": {
    "ok": true, 
    "status": 200, 
    "body": {}
  },
  "extraResponseData": {
    "ok": true, 
    "status": 200, 
    "body": {}
  }
}
  • requestBody is JSON or FormData object for POST requests and undefined for GET requests.
  • info — additional data that set by a request caller.
    • Product forms and Controls attach the initiator property to the info parameter. The initiator keeps the HTMLElement object of the form or control.
    • If there is a cancel property of the info parameter and cancel property is true, then the request will not be performed and the responseData will not exist.
  • responseData — the response on the request. ok is true if the response was successful (status in the range 200-299).
  • for /cart/add.js requests Liquid Ajax Cart performs an extra POST request to the /cart/update.js endpoint to get the updated cart state. extraResponseData object contains the response of the extra request.
  • Sometimes Liquid Ajax Cart performs an additional Shopify POST /cart/update.js request and saves the response in the extraResponseData object. The additional request happens if:
    • there were a /cart/add.js request that doesn’t return the cart JSON-data — the additional /cart/update.js request will bring the updated cart state,
    • there were a request with more than 5 sections — the additional /cart/update.js request will bring the rest sections’ HTML.
  • If the request couldn’t be performed and response wasn’t received because, for example, internet was disconnected — the responseData will not exist but fetchError will be there instead:

    {
      "endpoint": "/cart/add.js",
      "requestBody": {"items": [{"id": 40934235668668, "quantity": 1}], "sections": "my-cart"},
      "requestType": "add",
      "info": {},
      "fetchError": {
        "message": "Failed to fetch",
        "stack": "TypeError: Failed to fetch\n    at e.fetch (h..."
      }
    }
    

Reference