---
title: pos.cart-update.event.observe
description: |-
  Observes cart updates during active transactions, triggering whenever merchants add, remove, or modify line items. Use this target for real-time responses to cart changes like dynamic pricing, inventory validation, or promotional offer applications based on current cart contents.

  Extensions at this target receive complete cart data including line items, totals, discounts, and customer information whenever the cart state changes.
api_version: 2025-10
api_name: pos-ui-extensions
source_url:
  html: https://shopify.dev/docs/api/pos-ui-extensions/latest/targets/cart-details/pos-cart-update-event-observe
  md: https://shopify.dev/docs/api/pos-ui-extensions/latest/targets/cart-details/pos-cart-update-event-observe.md
---

pos.​cart-update.​event.​observe

Not supported in this version.