# pos.cart-update.event.observe An event extension target that observes cart updates > Note: > This is part of a POS UI Extensions developer preview. More information to come. ## CartUpdateEventData The data object provided to this extension target. ### CartUpdateEventData ### cart value: `Cart` ### connectivity value: `ConnectivityState` ### device value: `Device` ### locale value: `string` ### session value: `Session` ### Cart ### cartDiscount value: `Discount` ### cartDiscounts value: `Discount[]` ### customer value: `Customer` ### grandTotal value: `string` ### lineItems value: `LineItem[]` ### note value: `string` ### properties value: `Record<string, string>` ### subtotal value: `string` ### taxTotal value: `string` ### Discount ### amount value: `number` ### currency value: `string` ### discountDescription value: `string` ### type value: `string` ### Customer ### id value: `number` ### LineItem ### attributedUserId value: `number` ### discounts value: `Discount[]` ### isGiftCard value: `boolean` ### price value: `number` ### productId value: `number` ### properties value: `{ [key: string]: string; }` ### quantity value: `number` ### sku value: `string` ### taxable value: `boolean` ### taxLines value: `TaxLine[]` ### title value: `string` ### uuid value: `string` ### variantId value: `number` ### vendor value: `string` ### TaxLine ### enabled value: `boolean` ### price value: `Money` ### rate value: `number` ### rateRange value: `{ min: number; max: number; }` ### title value: `string` ### uuid value: `string` ### Money ### amount value: `number` ### currency value: `string` ### ConnectivityState ### internetConnected value: `ConnectivityStateSeverity` Whether the device is connected to the internet ### Device ### deviceId value: `number` The ID of the device ### isTablet value: `boolean` Whether the device is a tablet ### name value: `string` The name of the device ### Session ### currency value: `CurrencyCode` The currency code associated with the location currently in on POS. ### locationId value: `number` The location ID associated with the POS' current location. ### shopDomain value: `string` The shop domain associated with the shop currently logged into POS. ### shopId value: `number` The shop ID associated with the shop currently logged into POS. ### staffMemberId value: `number` The staff ID who is currently pinned into the POS. Note that this staff member ID may be different to the User ID, as the staff member who enters their PIN may be different to the User who logged onto POS. ### userId value: `number` The user ID associated with the Shopify account currently authenticated on POS.