Choose a version:

useSubscription()

Subscribes to the special wrapper type that all "changeable" values in the checkout use. This hook extracts the most recent value from that object, and subscribes to update the value when changes occur in the checkout.

Note

> As of version 2025-10, you no longer need this hook. When you access .value > (instead of .current) on subscribable properties, Preact will automatically > re-render as .value changes.

Anchor to useSubscription
useSubscription(
subscription
)

Anchor to useSubscription-parametersParameters

Anchor to subscription subscription <Value> required

Anchor to useSubscription-returnsReturns

Value

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
Subscribes to value changes and calls the provided function whenever the value updates. Returns an unsubscribe function to clean up the subscription. Use to automatically react to changes in the signal's value.
```
(fn: (value: T) => void) => () => void
```
value
The current value of the signal. This property provides immediate access to the current value without requiring subscription setup. Use for one-time value checks or initial setup.
```
T
```

Examples

Preact

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

import {render} from 'preact';

export default function extension() {

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

}

function Extension() {

// As of version 2025-10, you no longer need the `useSubscription` hook.

// When you access `.value` on subscribable properties,

// Preact will automatically re-render as `.value` changes.

return (

<s-banner>

{shopify.cost.totalAmount.value.amount}

</s-banner>

);

}

Examples

Subscribing to changes

Preact

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

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

function Extension() {
  // As of version 2025-10, you no longer need the `useSubscription` hook.
  // When you access `.value` on subscribable properties,
  // Preact will automatically re-render as `.value` changes.
  return (
    <s-banner>
      {shopify.cost.totalAmount.value.amount}
    </s-banner>
  );
}