Cart operations extension - EXPRESSO Docs

The Cart Operations extension lets you inspect the current cart and return native cart mutations.

Exported function

Export onCartChanged from the extension module:

export function onCartChanged(
  cart: Cart
): CartOperation[] | Promise<CartOperation[]> {
  return [];
}

Use CartOperations to create the returned mutations. See Cart operations and Data models.

Execution behavior

Native can invoke the hook repeatedly, up to three passes.
Each pass receives the latest cart after previously returned operations are applied.
Conflicting operations are suppressed by the native runner.
Return an empty array when no change is needed.
Async work must complete within the extension’s three-second execution budget.

import { CartOperations } from "@napps/component-extension";

export async function onCartChanged(cart: Cart) {
  const item = cart.lineItems.find((line) => line.product?.vendor === "Example");

  if (!item) {
    return [];
  }

  return [CartOperations.updateLineItem(item.id, undefined, undefined, 1)];
}

Keep the hook idempotent. Repeated passes should converge instead of continuously producing new operations.