> For the complete documentation index, see [llms.txt](https://docs.chord.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.chord.co/chord-oms/shopify/developer-tools/gatsby/sdk-reference/usecart.md).

# useCart

The `useCart` hook returns a series of methods for interacting with the Shopify shopping cart.

```javascript
import { useCart } from '@chordcommerce/gatsby-theme-performance'

const {
  cart,
  addPromoCode,
  addToCart,
  applyGiftCard,
  checkout,
  loadCart,
  modifyQuantity,
  removeFromCart,
  removeGiftCard,
  removePromoCode
} = useCart()
```

### cart

Represents the current shopping cart.

**Example:**

```javascript
const { cart } = useCart()
```

### addPromoCode()

Applies a promo code to the current order.

**Example:**

```javascript
const promoCode = '50off'
await addPromoCode(promoCode)
```

### addToCart()

Adds an item to the current order.

**Example:**

```javascript
const variantId = '123'
const quantity = 1
await addToCart(variantId, quantity)
```

### applyGiftCard()

Applies a gift card to the current order.

**Example:**

```javascript
const giftCardCode = 'xxxyyyzzz'
await applyGiftCard(giftCardCode)
```

### checkout()

Redirects the browser to Shopify checkout.

**Example:**

```javascript
await checkout()
```

### loadCart()

Reloads the current shopping cart. This is automatically called on every page load and with every other `useCart` method.

**Example:**

```javascript
await loadCart()
```

### modifyQuantity()

Updates the quantity of a line item in the current order.

**Example:**

```javascript
const lineItemId = '123'
const quantity = 2
await modifyQuantity(lineItemId, quantity)
```

### modifyLineItem()

Updates a line item in the current order.

**Example:**

```javascript
const lineItemId = '123'

// update line item quantity
await modifyQuantity(lineItemId, {
  quantity: 2,
})

// update line item customAttributes
await modifyQuantity(lineItemId, {
  customAttributes: [
    {
      key: 'Est. Shipping Date',
      value: 'March 24, 2022',
    }
  ],
})
```

### removeFromCart()

Removes a line item from the current order.

**Example:**

```javascript
const lineItemId = '123'
await removeFromCart(lineItemId)
```

### removeGiftCard()

Removes a gift card from the current order.

**Example:**

```javascript
const giftCardCode = 'xxxyyyzzz'
await removeGiftCard(giftCardCode)
```

### removePromoCode()

Removes a promo code from the current order.

**Example:**

```javascript
const promoCode = '50off'
await removePromoCode(promoCode)
```

## \`\`


---

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