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Liquid Ajax Cart adds the js-ajax-cart-request-in-progress CSS class to the body if there are one or more Shopify Cart API requests in progress.

Some controls become inactive when Liquid Ajax Cart is sending an Ajax request so you can show a loading indicator or make the controls visually disabled using the js-ajax-cart-request-in-progress CSS class.

Under the hood Liquid Ajax Cart checks the status.requestInProgress property of the State object and adds the CSS class if the status.requestInProgress value is true and removes the CSS class if the value is false.