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Cart Instructions
API

Instructions used to create the checkout.

Anchor to standardapiStandardApi

The base API object provided to purchase extension targets.

Anchor to instructions instructions <> required: The cart instructions used to create the checkout and possibly limit extension capabilities.

These instructions should be checked prior to performing any actions that may be affected by them.

For example, if you intend to add a discount code via the applyDiscountCodeChange method, check discounts.canUpdateDiscountCodes to ensure it's supported in this checkout.

Caution
As of version 2024-07, UI extension code must check for instructions before calling select APIs in case those APIs are not available. See the update guide for more information.

SubscribableSignalLike

Represents a read-only value managed on the main thread that an extension can subscribe to. Example: Checkout uses this to manage the state of an object and communicate state changes to extensions running in a sandboxed web worker. This interface is compatible with [Preact's ReadonlySignal](https://github.com/preactjs/signals/blob/a023a132a81bd4ba4a0bebb8cbbeffbd8c8bbafc/packages/core/src/index.ts#L700-L709). Some fields are deprecated but still supported for backwards compatibility. In version 2025-10, [`StatefulRemoteSubscribable`](https://github.com/Shopify/remote-dom/blob/03929aa8418a89d41d294005f219837582718df8/packages/async-subscription/src/types.ts#L17) was replaced with `ReadonlySignalLike`. Checkout will remove the old fields some time in the future.

current
```
T
```
destroy
```
() => Promise<void>
```
subscribe
```
(fn: (value: T) => void) => () => void
```
value
```
T
```

export interface SubscribableSignalLike<T> extends ReadonlySignalLike<T> {
  /**
   * @deprecated Use `.value` instead.
   */
  readonly current: T;
  /**
   * @deprecated No longer needed. Use Preact Signal management instead.
   */
  destroy(): Promise<void>;
}

CartInstructions

attributes
Cart instructions related to cart attributes.
```
AttributesCartInstructions
```
delivery
Cart instructions related to delivery.
```
DeliveryCartInstructions
```
discounts
Cart instructions related to discounts.
```
DiscountsCartInstructions
```
lines
Cart instructions related to cart lines.
```
CartLinesCartInstructions
```
metafields
Cart instructions related to metafields.
```
MetafieldsCartInstructions
```
notes
Cart instructions related to notes.
```
NotesCartInstructions
```

export interface CartInstructions {
  /**
   * Cart instructions related to cart attributes.
   */
  attributes: AttributesCartInstructions;

  /**
   * Cart instructions related to delivery.
   */
  delivery: DeliveryCartInstructions;

  /**
   * Cart instructions related to discounts.
   */
  discounts: DiscountsCartInstructions;

  /**
   * Cart instructions related to cart lines.
   */
  lines: CartLinesCartInstructions;

  /**
   * Cart instructions related to metafields.
   */
  metafields: MetafieldsCartInstructions;

  /**
   * Cart instructions related to notes.
   */
  notes: NotesCartInstructions;
}

AttributesCartInstructions

canUpdateAttributes
Indicates whether or not cart attributes can be updated.
```
boolean
```

export interface AttributesCartInstructions {
  /**
   * Indicates whether or not cart attributes can be updated.
   */
  canUpdateAttributes: boolean;
}

DeliveryCartInstructions

canSelectCustomAddress
Indicates whether a buyer can select a custom address. When true, this implies extensions can update the delivery address.
```
boolean
```

export interface DeliveryCartInstructions {
  /**
   * Indicates whether a buyer can select a custom address.
   *
   * When true, this implies extensions can update the delivery address.
   */
  canSelectCustomAddress: boolean;
}

DiscountsCartInstructions

canUpdateDiscountCodes
Indicates whether or not discount codes can be updated.
```
boolean
```

export interface DiscountsCartInstructions {
  /**
   * Indicates whether or not discount codes can be updated.
   */
  canUpdateDiscountCodes: boolean;
}

CartLinesCartInstructions

canAddCartLine
Indicates whether or not new cart lines can be added.
```
boolean
```
canRemoveCartLine
Indicates whether or not cart lines can be removed.
```
boolean
```
canUpdateCartLine
Indicates whether or not cart lines can be updated.
```
boolean
```

export interface CartLinesCartInstructions {
  /**
   * Indicates whether or not new cart lines can be added.
   */
  canAddCartLine: boolean;

  /**
   * Indicates whether or not cart lines can be removed.
   */
  canRemoveCartLine: boolean;

  /**
   * Indicates whether or not cart lines can be updated.
   */
  canUpdateCartLine: boolean;
}

MetafieldsCartInstructions

canDeleteCartMetafield
Indicates whether or not cart metafields can be deleted.
```
boolean
```
canSetCartMetafields
Indicates whether or not cart metafields can be added or updated.
```
boolean
```

export interface MetafieldsCartInstructions {
  /**
   * Indicates whether or not cart metafields can be added or updated.
   */
  canSetCartMetafields: boolean;

  /**
   * Indicates whether or not cart metafields can be deleted.
   */
  canDeleteCartMetafield: boolean;
}

NotesCartInstructions

canUpdateNote
Indicates whether or not notes can be updated.
```
boolean
```

export interface NotesCartInstructions {
  /**
   * Indicates whether or not notes can be updated.
   */
  canUpdateNote: boolean;
}

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Anchor to useInstructions
useInstructions()

Returns the cart instructions used to create the checkout and possibly limit extension capabilities.

Anchor to useInstructions-returnsReturns

CartInstructions

attributes: Cart instructions related to cart attributes.
delivery: Cart instructions related to delivery.
discounts: Cart instructions related to discounts.
lines: Cart instructions related to cart lines.
metafields: Cart instructions related to metafields.
notes: Cart instructions related to notes.

CartInstructions

attributes
Cart instructions related to cart attributes.
```
AttributesCartInstructions
```
delivery
Cart instructions related to delivery.
```
DeliveryCartInstructions
```
discounts
Cart instructions related to discounts.
```
DiscountsCartInstructions
```
lines
Cart instructions related to cart lines.
```
CartLinesCartInstructions
```
metafields
Cart instructions related to metafields.
```
MetafieldsCartInstructions
```
notes
Cart instructions related to notes.
```
NotesCartInstructions
```

export interface CartInstructions {
  /**
   * Cart instructions related to cart attributes.
   */
  attributes: AttributesCartInstructions;

  /**
   * Cart instructions related to delivery.
   */
  delivery: DeliveryCartInstructions;

  /**
   * Cart instructions related to discounts.
   */
  discounts: DiscountsCartInstructions;

  /**
   * Cart instructions related to cart lines.
   */
  lines: CartLinesCartInstructions;

  /**
   * Cart instructions related to metafields.
   */
  metafields: MetafieldsCartInstructions;

  /**
   * Cart instructions related to notes.
   */
  notes: NotesCartInstructions;
}

AttributesCartInstructions

canUpdateAttributes
Indicates whether or not cart attributes can be updated.
```
boolean
```

export interface AttributesCartInstructions {
  /**
   * Indicates whether or not cart attributes can be updated.
   */
  canUpdateAttributes: boolean;
}

DeliveryCartInstructions

canSelectCustomAddress
Indicates whether a buyer can select a custom address. When true, this implies extensions can update the delivery address.
```
boolean
```

export interface DeliveryCartInstructions {
  /**
   * Indicates whether a buyer can select a custom address.
   *
   * When true, this implies extensions can update the delivery address.
   */
  canSelectCustomAddress: boolean;
}

DiscountsCartInstructions

canUpdateDiscountCodes
Indicates whether or not discount codes can be updated.
```
boolean
```

export interface DiscountsCartInstructions {
  /**
   * Indicates whether or not discount codes can be updated.
   */
  canUpdateDiscountCodes: boolean;
}

CartLinesCartInstructions

canAddCartLine
Indicates whether or not new cart lines can be added.
```
boolean
```
canRemoveCartLine
Indicates whether or not cart lines can be removed.
```
boolean
```
canUpdateCartLine
Indicates whether or not cart lines can be updated.
```
boolean
```

export interface CartLinesCartInstructions {
  /**
   * Indicates whether or not new cart lines can be added.
   */
  canAddCartLine: boolean;

  /**
   * Indicates whether or not cart lines can be removed.
   */
  canRemoveCartLine: boolean;

  /**
   * Indicates whether or not cart lines can be updated.
   */
  canUpdateCartLine: boolean;
}

MetafieldsCartInstructions

canDeleteCartMetafield
Indicates whether or not cart metafields can be deleted.
```
boolean
```
canSetCartMetafields
Indicates whether or not cart metafields can be added or updated.
```
boolean
```

export interface MetafieldsCartInstructions {
  /**
   * Indicates whether or not cart metafields can be added or updated.
   */
  canSetCartMetafields: boolean;

  /**
   * Indicates whether or not cart metafields can be deleted.
   */
  canDeleteCartMetafield: boolean;
}

NotesCartInstructions

canUpdateNote
Indicates whether or not notes can be updated.
```
boolean
```

export interface NotesCartInstructions {
  /**
   * Indicates whether or not notes can be updated.
   */
  canUpdateNote: boolean;
}

Was this section helpful?

Discounts

Preact

import '@shopify/ui-extensions/preact';

import {render} from 'preact';

export default function extension() {

render(<Extension />, document.body);

}

function Extension() {

if (

shopify.instructions.value.discounts

.canUpdateDiscountCodes

) {

return (

<s-button

onClick={() =>

shopify.applyDiscountCodeChange({

type: 'addDiscountCode',

code: 'FREE_SHIPPING',

})

}

Apply your loyalty discount

</s-button>

);

} else {

return (

<s-banner tone="warning">

Loyalty discounts are unavailable

</s-banner>

);

}

Examples

Discounts

Description

Check `instructions.discounts.canUpdateDiscountCodes` before calling `applyDiscountCodeChange()`.

Preact

import '@shopify/ui-extensions/preact';
import {render} from 'preact';

export default function extension() {
  render(<Extension />, document.body);
}

function Extension() {
  if (
    shopify.instructions.value.discounts
      .canUpdateDiscountCodes
  ) {
    return (
      <s-button
        onClick={() =>
          shopify.applyDiscountCodeChange({
            type: 'addDiscountCode',
            code: 'FREE_SHIPPING',
          })
        }
      >
        Apply your loyalty discount
      </s-button>
    );
  } else {
    return (
      <s-banner tone="warning">
        Loyalty discounts are unavailable
      </s-banner>
    );
  }
}

Anchor to examplesExamples

Use the cart instructions API to determine if the affected APIs are available in checkout.

Anchor to example-attributesAttributes

Check instructions.attributes.canUpdateAttributes before calling applyAttributeChange().

Anchor to example-deliveryDelivery

Check instructions.delivery.canSelectCustomAddress before calling applyShippingAddressChange(). When true, this instruction implies that extensions can change the shipping address.

Anchor to example-discountsDiscounts

Check instructions.discounts.canUpdateDiscountCodes before calling applyDiscountCodeChange().

Anchor to example-linesLines

Check instructions.lines.canAddCartLine or instructions.lines.canRemoveCartLine or instructions.lines.canUpdateCartLine before calling applyCartLinesChange().

Anchor to example-metafieldsMetafields

Check instructions.metafields.canSetCartMetafields or instructions.metafields.canDeleteCartMetafields before calling applyMetafieldChange() if you are working with cart metafields.

Anchor to example-notesNotes

Check instructions.notes.canUpdateNote before calling applyNoteChange().

Was this section helpful?

Attributes

Preact

import '@shopify/ui-extensions/preact';

import {render} from 'preact';

export default function extension() {

render(<Extension />, document.body);

}

function Extension() {

if (

shopify.instructions.value.attributes

.canUpdateAttributes

) {

return (

<s-button

onClick={() =>

shopify.applyAttributeChange({

type: 'updateAttribute',

key: 'loyaltyPoints',

value: '100',

})

}

Apply 100 loyalty points

</s-button>

);

} else {

return (

<s-banner tone="warning">

Loyalty points are unavailable

</s-banner>

);

}

Examples

Attributes

Description

Check `instructions.attributes.canUpdateAttributes` before calling `applyAttributeChange()`.

Preact

import '@shopify/ui-extensions/preact';
import {render} from 'preact';

export default function extension() {
  render(<Extension />, document.body);
}

function Extension() {
  if (
    shopify.instructions.value.attributes
      .canUpdateAttributes
  ) {
    return (
      <s-button
        onClick={() =>
          shopify.applyAttributeChange({
            type: 'updateAttribute',
            key: 'loyaltyPoints',
            value: '100',
          })
        }
      >
        Apply 100 loyalty points
      </s-button>
    );
  } else {
    return (
      <s-banner tone="warning">
        Loyalty points are unavailable
      </s-banner>
    );
  }
}

Delivery

Description

Check `instructions.delivery.canSelectCustomAddress` before calling `applyShippingAddressChange()`. When `true`, this instruction implies that extensions can change the shipping address.

Preact

import '@shopify/ui-extensions/preact';
import {render} from 'preact';

export default function extension() {
  render(<Extension />, document.body);
}

function Extension() {
  if (
    shopify.instructions.value.delivery
      .canSelectCustomAddress
  ) {
    return (
      <s-button
        onClick={() =>
          shopify.applyShippingAddressChange({
            type: 'updateShippingAddress',
            address: {
              zip: '90201',
            },
          })
        }
      >
        Change your postal code
      </s-button>
    );
  } else {
    return (
      <s-banner tone="warning">
        Shipping address cannot be modified
      </s-banner>
    );
  }
}

Discounts

Description

Check `instructions.discounts.canUpdateDiscountCodes` before calling `applyDiscountCodeChange()`.

Preact

import '@shopify/ui-extensions/preact';
import {render} from 'preact';

export default function extension() {
  render(<Extension />, document.body);
}

function Extension() {
  if (
    shopify.instructions.value.discounts
      .canUpdateDiscountCodes
  ) {
    return (
      <s-button
        onClick={() =>
          shopify.applyDiscountCodeChange({
            type: 'addDiscountCode',
            code: 'FREE_SHIPPING',
          })
        }
      >
        Apply your loyalty discount
      </s-button>
    );
  } else {
    return (
      <s-banner tone="warning">
        Loyalty discounts are unavailable
      </s-banner>
    );
  }
}

Lines

Description

Check `instructions.lines.canAddCartLine` or `instructions.lines.canRemoveCartLine` or `instructions.lines.canUpdateCartLine` before calling `applyCartLinesChange()`.

Preact

import '@shopify/ui-extensions/preact';
import {render} from 'preact';

export default function extension() {
  render(<Extension />, document.body);
}

function Extension() {
  if (
    shopify.instructions.value.lines
      .canAddCartLine
  ) {
    return (
      <s-button
        onClick={() =>
          shopify.applyCartLinesChange({
            type: 'addCartLine',
            merchandiseId:
              'gid://shopify/product/1234',
            quantity: 1,
          })
        }
      >
        Add a free gift to your order
      </s-button>
    );
  } else {
    return (
      <s-banner tone="warning">
        The products in your cart cannot be
        modified
      </s-banner>
    );
  }
}

Metafields

Description

Check `instructions.metafields.canSetCartMetafields` or `instructions.metafields.canDeleteCartMetafields` before calling `applyMetafieldChange()` if you are working with cart metafields.

Preact

import '@shopify/ui-extensions/preact';
import {render} from 'preact';

export default function extension() {
  render(<Extension />, document.body);
}

function Extension() {
  if (
    shopify.instructions.value.metafields
      .canSetCartMetafields
  ) {
    return (
      <s-button
        onClick={() =>
          shopify.applyMetafieldChange({
            type: 'updateCartMetafield',
            metafield: {
              namespace: 'loyalty',
              key: 'loyaltyPoints',
              value: '100',
              type: 'string',
            },
          })
        }
      >
        Apply 100 loyalty points
      </s-button>
    );
  } else {
    return (
      <s-banner tone="warning">
        Loyalty points are unavailable
      </s-banner>
    );
  }
}

Notes

Description

Check `instructions.notes.canUpdateNote` before calling `applyNoteChange()`.

Preact

import '@shopify/ui-extensions/preact';
import {render} from 'preact';

export default function extension() {
  render(<Extension />, document.body);
}

function Extension() {
  if (
    shopify.instructions.value.notes.canUpdateNote
  ) {
    return (
      <s-button
        onClick={() =>
          shopify.applyNoteChange({
            type: 'updateNote',
            note: 'Please include a free gift.',
          })
        }
      >
        Include a free gift with your order
      </s-button>
    );
  } else {
    return (
      <s-banner tone="warning">
        Free gifts cannot be added to this order
      </s-banner>
    );
  }
}