---
title: Buyer Journey
description: The API for interacting with the buyer journey.
api_version: 2025-10
api_name: checkout-ui-extensions
source_url:
  html: https://shopify.dev/docs/api/checkout-ui-extensions/latest/apis/buyer-journey
  md: https://shopify.dev/docs/api/checkout-ui-extensions/latest/apis/buyer-journey.md
---

# Buyer JourneyAPI

The API for interacting with the buyer journey.

## StandardApi

The base API object provided to `purchase` extension targets.

* buyerJourney

  BuyerJourney

  required

  Provides details on the buyer's progression through the checkout.

  Refer to [buyer journey](https://shopify.dev/docs/api/checkout-ui-extensions/apis/buyer-journey#examples) examples for more information.

### BuyerJourney

Provides details on the buyer's progression through the checkout.

* activeStep

  What step of checkout the buyer is currently on.

  ```ts
  SubscribableSignalLike<BuyerJourneyStepReference | undefined>
  ```

* completed

  This subscribable value will be true if the buyer completed submitting their order. For example, when viewing the \*\*Order status\*\* page after submitting payment, the buyer will have completed their order.

  ```ts
  SubscribableSignalLike<boolean>
  ```

* intercept

  Installs a function for intercepting and preventing progress on checkout. This returns a promise that resolves to a teardown function. Calling the teardown function will remove the interceptor. To block checkout progress, you must set the \[block\_progress]\(/docs/api/checkout-ui-extensions/configuration#block-progress) capability in your extension's configuration. If you do, then you're expected to inform the buyer why navigation was blocked, either by passing validation errors to the checkout UI or rendering the errors in your extension.

  ```ts
  (interceptor: Interceptor) => Promise<() => void>
  ```

* steps

  All possible steps a buyer can take to complete the checkout. These steps may vary depending on the type of checkout or the shop's configuration.

  ```ts
  SubscribableSignalLike<BuyerJourneyStep[]>
  ```

```ts
export interface BuyerJourney {
  /**
   * Installs a function for intercepting and preventing progress on checkout.
   *
   * This returns a promise that resolves to a teardown function. Calling the
   * teardown function will remove the interceptor.
   *
   * To block checkout progress, you must set the [block_progress](/docs/api/checkout-ui-extensions/configuration#block-progress)
   * capability in your extension's configuration.
   *
   * If you do, then you're expected to inform the buyer why navigation was blocked,
   * either by passing validation errors to the checkout UI or rendering the errors in your extension.
   */
  intercept(interceptor: Interceptor): Promise<() => void>;

  /**
   * This subscribable value will be true if the buyer completed submitting their order.
   *
   * For example, when viewing the **Order status** page after submitting payment, the buyer will have completed their order.
   */
  completed: SubscribableSignalLike<boolean>;
  /**
   * All possible steps a buyer can take to complete the checkout. These steps may vary depending on the type of checkout or the shop's configuration.
   */
  steps: SubscribableSignalLike<BuyerJourneyStep[]>;
  /**
   * What step of checkout the buyer is currently on.
   */
  activeStep: SubscribableSignalLike<BuyerJourneyStepReference | undefined>;
}
```

### 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

  ```ts
  T
  ```

* destroy

  ```ts
  () => Promise<void>
  ```

* subscribe

  ```ts
  (fn: (value: T) => void) => () => void
  ```

* value

  ```ts
  T
  ```

```ts
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>;
}
```

### BuyerJourneyStepReference

What step of checkout the buyer is currently on.

* handle

  The handle that uniquely identifies the buyer journey step.

  ```ts
  BuyerJourneyStepHandle
  ```

```ts
interface BuyerJourneyStepReference {
  /**
   * The handle that uniquely identifies the buyer journey step.
   */
  handle: BuyerJourneyStepHandle;
}
```

### BuyerJourneyStepHandle

\| handle | Description | |---|---| | \`cart\` | The cart page. | | \`checkout\` | A one-page checkout, including Shop Pay. | | \`information\` | The contact information step of a three-page checkout. | | \`shipping\` | The shipping step of a three-page checkout. | | \`payment\` | The payment step of a three-page checkout. | | \`review\` | The step after payment where the buyer confirms the purchase. Not all shops are configured to have a review step. | | \`thank-you\` | The page displayed after the purchase, thanking the buyer. | | \`unknown\` | An unknown step in the buyer journey. |

```ts
'cart' | 'checkout' | 'information' | 'shipping' | 'payment' | 'review' | 'thank-you' | 'unknown'
```

### Interceptor

A function for intercepting and preventing navigation on checkout. You can block navigation by returning an object with \`{behavior: 'block', reason: InvalidResultReason.InvalidExtensionState, errors?: ValidationErrors\[]}\`. If you do, then you're expected to also update some part of your UI to reflect the reason why navigation was blocked, either by targeting checkout UI fields, passing errors to the page level or rendering the errors in your extension.

* interceptorProps

  ```ts
  InterceptorProps
  ```

InterceptorRequest | Promise\<InterceptorRequest>

```ts
InterceptorRequest | Promise<InterceptorRequest>
```

```ts
(
  interceptorProps: InterceptorProps,
) => InterceptorRequest | Promise<InterceptorRequest>
```

### InterceptorProps

* canBlockProgress

  Whether the interceptor has the capability to block a buyer's progress through checkout. This ability might be granted by a merchant in differing checkout contexts.

  ```ts
  boolean
  ```

```ts
export interface InterceptorProps {
  /**
   * Whether the interceptor has the capability to block a buyer's progress through
   * checkout. This ability might be granted by a merchant in differing checkout contexts.
   */
  canBlockProgress: boolean;
}
```

### InterceptorRequest

```ts
InterceptorRequestAllow | InterceptorRequestBlock
```

### InterceptorRequestAllow

* behavior

  Indicates that the interceptor will allow the buyer's journey to continue.

  ```ts
  'allow'
  ```

* perform

  This callback is called when all interceptors finish. We recommend setting errors or reasons for blocking at this stage, so that all the errors in the UI show up at once.

  ```ts
  (result: InterceptorResult) => void | Promise<void>
  ```

```ts
interface InterceptorRequestAllow {
  /**
   * Indicates that the interceptor will allow the buyer's journey to continue.
   */
  behavior: 'allow';

  /**
   * This callback is called when all interceptors finish. We recommend
   * setting errors or reasons for blocking at this stage, so that all the errors in
   * the UI show up at once.
   * @param result InterceptorResult with behavior as either 'allow' or 'block'
   */
  perform?(result: InterceptorResult): void | Promise<void>;
}
```

### InterceptorResult

```ts
InterceptorResultAllow | InterceptorResultBlock
```

### InterceptorResultAllow

* behavior

  Indicates that the buyer was allowed to progress through checkout.

  ```ts
  'allow'
  ```

```ts
interface InterceptorResultAllow {
  /**
   * Indicates that the buyer was allowed to progress through checkout.
   */
  behavior: 'allow';
}
```

### InterceptorResultBlock

* behavior

  Indicates that some part of the checkout UI intercepted and prevented the buyer’s progress. The buyer typically needs to take some action to resolve this issue and to move on to the next step.

  ```ts
  'block'
  ```

```ts
interface InterceptorResultBlock {
  /**
   * Indicates that some part of the checkout UI intercepted and prevented
   * the buyer’s progress. The buyer typically needs to take some action
   * to resolve this issue and to move on to the next step.
   */
  behavior: 'block';
}
```

### InterceptorRequestBlock

* behavior

  Indicates that the interceptor will block the buyer's journey from continuing.

  ```ts
  'block'
  ```

* errors

  Used to pass errors to the checkout UI, outside your extension's UI boundaries.

  ```ts
  ValidationError[]
  ```

* perform

  This callback is called when all interceptors finish. We recommend setting errors or reasons for blocking at this stage, so that all the errors in the UI show up at once.

  ```ts
  (result: InterceptorResult) => void | Promise<void>
  ```

* reason

  The reason for blocking the interceptor request. This value isn't presented to the buyer, so it doesn't need to be localized. The value is used only for Shopify’s own internal debugging and metrics.

  ```ts
  string
  ```

```ts
interface InterceptorRequestBlock {
  /**
   * Indicates that the interceptor will block the buyer's journey from continuing.
   */
  behavior: 'block';

  /**
   * The reason for blocking the interceptor request. This value isn't presented to
   * the buyer, so it doesn't need to be localized. The value is used only for Shopify’s
   * own internal debugging and metrics.
   */
  reason: string;

  /**
   * Used to pass errors to the checkout UI, outside your extension's UI boundaries.
   */
  errors?: ValidationError[];

  /**
   * This callback is called when all interceptors finish. We recommend
   * setting errors or reasons for blocking at this stage, so that all the errors in
   * the UI show up at once.
   * @param result InterceptorResult with behavior as either 'allow' or 'block'
   */
  perform?(result: InterceptorResult): void | Promise<void>;
}
```

### ValidationError

* message

  Error message to be displayed to the buyer.

  ```ts
  string
  ```

* target

  The checkout UI field that the error is associated with. Example: \`$.cart.deliveryGroups\[0].deliveryAddress.countryCode\` See the \[supported targets]\(/docs/api/functions/reference/cart-checkout-validation/graphql#supported-targets) for more information.

  ```ts
  string
  ```

```ts
export interface ValidationError {
  /**
   * Error message to be displayed to the buyer.
   */
  message: string;
  /**
   * The checkout UI field that the error is associated with.
   *
   * Example: `$.cart.deliveryGroups[0].deliveryAddress.countryCode`
   *
   * See the [supported targets](/docs/api/functions/reference/cart-checkout-validation/graphql#supported-targets)
   * for more information.
   */
  target?: string;
}
```

### BuyerJourneyStep

* disabled

  The disabled state of the buyer journey step. This value will be true if the buyer has not reached the step yet. For example, if the buyer has not reached the \`shipping\` step yet, \`shipping\` would be disabled.

  ```ts
  boolean
  ```

* handle

  The handle that uniquely identifies the buyer journey step.

  ```ts
  BuyerJourneyStepHandle
  ```

* label

  The localized label of the buyer journey step.

  ```ts
  string
  ```

* to

  The url of the buyer journey step. This property leverages the \`shopify:\` protocol E.g. \`shopify:cart\` or \`shopify:checkout/information\`.

  ```ts
  string
  ```

```ts
export interface BuyerJourneyStep {
  /**
   * The handle that uniquely identifies the buyer journey step.
   */
  handle: BuyerJourneyStepHandle;
  /**
   * The localized label of the buyer journey step.
   */
  label: string;
  /**
   * The url of the buyer journey step. This property leverages the `shopify:` protocol
   * E.g. `shopify:cart` or `shopify:checkout/information`.
   */
  to: string;
  /**
   * The disabled state of the buyer journey step. This value will be true if the buyer has not reached the step yet.
   *
   * For example, if the buyer has not reached the `shipping` step yet, `shipping` would be disabled.
   */
  disabled: boolean;
}
```

## use​Buyer​Journey()

Returns the buyerJourney details on buyer progression in checkout.

### Returns

* BuyerJourney

  ### BuyerJourney

  * activeStep

    SubscribableSignalLike\<BuyerJourneyStepReference | undefined>

    What step of checkout the buyer is currently on.

  * completed

    SubscribableSignalLike\<boolean>

    This subscribable value will be true if the buyer completed submitting their order.

    For example, when viewing the **Order status** page after submitting payment, the buyer will have completed their order.

  * intercept

    (interceptor: Interceptor) => Promise<() => void>

    Installs a function for intercepting and preventing progress on checkout.

    This returns a promise that resolves to a teardown function. Calling the teardown function will remove the interceptor.

    To block checkout progress, you must set the [block\_progress](https://shopify.dev/docs/api/checkout-ui-extensions/configuration#block-progress) capability in your extension's configuration.

    If you do, then you're expected to inform the buyer why navigation was blocked, either by passing validation errors to the checkout UI or rendering the errors in your extension.

  * steps

    SubscribableSignalLike\<BuyerJourneyStep\[]>

    All possible steps a buyer can take to complete the checkout. These steps may vary depending on the type of checkout or the shop's configuration.

### BuyerJourney

Provides details on the buyer's progression through the checkout.

* activeStep

  What step of checkout the buyer is currently on.

  ```ts
  SubscribableSignalLike<BuyerJourneyStepReference | undefined>
  ```

* completed

  This subscribable value will be true if the buyer completed submitting their order. For example, when viewing the \*\*Order status\*\* page after submitting payment, the buyer will have completed their order.

  ```ts
  SubscribableSignalLike<boolean>
  ```

* intercept

  Installs a function for intercepting and preventing progress on checkout. This returns a promise that resolves to a teardown function. Calling the teardown function will remove the interceptor. To block checkout progress, you must set the \[block\_progress]\(/docs/api/checkout-ui-extensions/configuration#block-progress) capability in your extension's configuration. If you do, then you're expected to inform the buyer why navigation was blocked, either by passing validation errors to the checkout UI or rendering the errors in your extension.

  ```ts
  (interceptor: Interceptor) => Promise<() => void>
  ```

* steps

  All possible steps a buyer can take to complete the checkout. These steps may vary depending on the type of checkout or the shop's configuration.

  ```ts
  SubscribableSignalLike<BuyerJourneyStep[]>
  ```

```ts
export interface BuyerJourney {
  /**
   * Installs a function for intercepting and preventing progress on checkout.
   *
   * This returns a promise that resolves to a teardown function. Calling the
   * teardown function will remove the interceptor.
   *
   * To block checkout progress, you must set the [block_progress](/docs/api/checkout-ui-extensions/configuration#block-progress)
   * capability in your extension's configuration.
   *
   * If you do, then you're expected to inform the buyer why navigation was blocked,
   * either by passing validation errors to the checkout UI or rendering the errors in your extension.
   */
  intercept(interceptor: Interceptor): Promise<() => void>;

  /**
   * This subscribable value will be true if the buyer completed submitting their order.
   *
   * For example, when viewing the **Order status** page after submitting payment, the buyer will have completed their order.
   */
  completed: SubscribableSignalLike<boolean>;
  /**
   * All possible steps a buyer can take to complete the checkout. These steps may vary depending on the type of checkout or the shop's configuration.
   */
  steps: SubscribableSignalLike<BuyerJourneyStep[]>;
  /**
   * What step of checkout the buyer is currently on.
   */
  activeStep: SubscribableSignalLike<BuyerJourneyStepReference | undefined>;
}
```

### 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

  ```ts
  T
  ```

* destroy

  ```ts
  () => Promise<void>
  ```

* subscribe

  ```ts
  (fn: (value: T) => void) => () => void
  ```

* value

  ```ts
  T
  ```

```ts
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>;
}
```

### BuyerJourneyStepReference

What step of checkout the buyer is currently on.

* handle

  The handle that uniquely identifies the buyer journey step.

  ```ts
  BuyerJourneyStepHandle
  ```

```ts
interface BuyerJourneyStepReference {
  /**
   * The handle that uniquely identifies the buyer journey step.
   */
  handle: BuyerJourneyStepHandle;
}
```

### BuyerJourneyStepHandle

\| handle | Description | |---|---| | \`cart\` | The cart page. | | \`checkout\` | A one-page checkout, including Shop Pay. | | \`information\` | The contact information step of a three-page checkout. | | \`shipping\` | The shipping step of a three-page checkout. | | \`payment\` | The payment step of a three-page checkout. | | \`review\` | The step after payment where the buyer confirms the purchase. Not all shops are configured to have a review step. | | \`thank-you\` | The page displayed after the purchase, thanking the buyer. | | \`unknown\` | An unknown step in the buyer journey. |

```ts
'cart' | 'checkout' | 'information' | 'shipping' | 'payment' | 'review' | 'thank-you' | 'unknown'
```

### Interceptor

A function for intercepting and preventing navigation on checkout. You can block navigation by returning an object with \`{behavior: 'block', reason: InvalidResultReason.InvalidExtensionState, errors?: ValidationErrors\[]}\`. If you do, then you're expected to also update some part of your UI to reflect the reason why navigation was blocked, either by targeting checkout UI fields, passing errors to the page level or rendering the errors in your extension.

* interceptorProps

  ```ts
  InterceptorProps
  ```

InterceptorRequest | Promise\<InterceptorRequest>

```ts
InterceptorRequest | Promise<InterceptorRequest>
```

```ts
(
  interceptorProps: InterceptorProps,
) => InterceptorRequest | Promise<InterceptorRequest>
```

### InterceptorProps

* canBlockProgress

  Whether the interceptor has the capability to block a buyer's progress through checkout. This ability might be granted by a merchant in differing checkout contexts.

  ```ts
  boolean
  ```

```ts
export interface InterceptorProps {
  /**
   * Whether the interceptor has the capability to block a buyer's progress through
   * checkout. This ability might be granted by a merchant in differing checkout contexts.
   */
  canBlockProgress: boolean;
}
```

### InterceptorRequest

```ts
InterceptorRequestAllow | InterceptorRequestBlock
```

### InterceptorRequestAllow

* behavior

  Indicates that the interceptor will allow the buyer's journey to continue.

  ```ts
  'allow'
  ```

* perform

  This callback is called when all interceptors finish. We recommend setting errors or reasons for blocking at this stage, so that all the errors in the UI show up at once.

  ```ts
  (result: InterceptorResult) => void | Promise<void>
  ```

```ts
interface InterceptorRequestAllow {
  /**
   * Indicates that the interceptor will allow the buyer's journey to continue.
   */
  behavior: 'allow';

  /**
   * This callback is called when all interceptors finish. We recommend
   * setting errors or reasons for blocking at this stage, so that all the errors in
   * the UI show up at once.
   * @param result InterceptorResult with behavior as either 'allow' or 'block'
   */
  perform?(result: InterceptorResult): void | Promise<void>;
}
```

### InterceptorResult

```ts
InterceptorResultAllow | InterceptorResultBlock
```

### InterceptorResultAllow

* behavior

  Indicates that the buyer was allowed to progress through checkout.

  ```ts
  'allow'
  ```

```ts
interface InterceptorResultAllow {
  /**
   * Indicates that the buyer was allowed to progress through checkout.
   */
  behavior: 'allow';
}
```

### InterceptorResultBlock

* behavior

  Indicates that some part of the checkout UI intercepted and prevented the buyer’s progress. The buyer typically needs to take some action to resolve this issue and to move on to the next step.

  ```ts
  'block'
  ```

```ts
interface InterceptorResultBlock {
  /**
   * Indicates that some part of the checkout UI intercepted and prevented
   * the buyer’s progress. The buyer typically needs to take some action
   * to resolve this issue and to move on to the next step.
   */
  behavior: 'block';
}
```

### InterceptorRequestBlock

* behavior

  Indicates that the interceptor will block the buyer's journey from continuing.

  ```ts
  'block'
  ```

* errors

  Used to pass errors to the checkout UI, outside your extension's UI boundaries.

  ```ts
  ValidationError[]
  ```

* perform

  This callback is called when all interceptors finish. We recommend setting errors or reasons for blocking at this stage, so that all the errors in the UI show up at once.

  ```ts
  (result: InterceptorResult) => void | Promise<void>
  ```

* reason

  The reason for blocking the interceptor request. This value isn't presented to the buyer, so it doesn't need to be localized. The value is used only for Shopify’s own internal debugging and metrics.

  ```ts
  string
  ```

```ts
interface InterceptorRequestBlock {
  /**
   * Indicates that the interceptor will block the buyer's journey from continuing.
   */
  behavior: 'block';

  /**
   * The reason for blocking the interceptor request. This value isn't presented to
   * the buyer, so it doesn't need to be localized. The value is used only for Shopify’s
   * own internal debugging and metrics.
   */
  reason: string;

  /**
   * Used to pass errors to the checkout UI, outside your extension's UI boundaries.
   */
  errors?: ValidationError[];

  /**
   * This callback is called when all interceptors finish. We recommend
   * setting errors or reasons for blocking at this stage, so that all the errors in
   * the UI show up at once.
   * @param result InterceptorResult with behavior as either 'allow' or 'block'
   */
  perform?(result: InterceptorResult): void | Promise<void>;
}
```

### ValidationError

* message

  Error message to be displayed to the buyer.

  ```ts
  string
  ```

* target

  The checkout UI field that the error is associated with. Example: \`$.cart.deliveryGroups\[0].deliveryAddress.countryCode\` See the \[supported targets]\(/docs/api/functions/reference/cart-checkout-validation/graphql#supported-targets) for more information.

  ```ts
  string
  ```

```ts
export interface ValidationError {
  /**
   * Error message to be displayed to the buyer.
   */
  message: string;
  /**
   * The checkout UI field that the error is associated with.
   *
   * Example: `$.cart.deliveryGroups[0].deliveryAddress.countryCode`
   *
   * See the [supported targets](/docs/api/functions/reference/cart-checkout-validation/graphql#supported-targets)
   * for more information.
   */
  target?: string;
}
```

### BuyerJourneyStep

* disabled

  The disabled state of the buyer journey step. This value will be true if the buyer has not reached the step yet. For example, if the buyer has not reached the \`shipping\` step yet, \`shipping\` would be disabled.

  ```ts
  boolean
  ```

* handle

  The handle that uniquely identifies the buyer journey step.

  ```ts
  BuyerJourneyStepHandle
  ```

* label

  The localized label of the buyer journey step.

  ```ts
  string
  ```

* to

  The url of the buyer journey step. This property leverages the \`shopify:\` protocol E.g. \`shopify:cart\` or \`shopify:checkout/information\`.

  ```ts
  string
  ```

```ts
export interface BuyerJourneyStep {
  /**
   * The handle that uniquely identifies the buyer journey step.
   */
  handle: BuyerJourneyStepHandle;
  /**
   * The localized label of the buyer journey step.
   */
  label: string;
  /**
   * The url of the buyer journey step. This property leverages the `shopify:` protocol
   * E.g. `shopify:cart` or `shopify:checkout/information`.
   */
  to: string;
  /**
   * The disabled state of the buyer journey step. This value will be true if the buyer has not reached the step yet.
   *
   * For example, if the buyer has not reached the `shipping` step yet, `shipping` would be disabled.
   */
  disabled: boolean;
}
```

## use​Buyer​Journey​Completed()

Returns `true` if the buyer completed submitting their order. For example, when viewing the **Order status** page after submitting payment, the buyer will have completed their order.

### Returns

* false | true

## use​Buyer​Journey​Intercept([interceptor](#usebuyerjourneyintercept-propertydetail-interceptor)​)

Installs a function for intercepting and preventing progress on checkout. To block checkout progress, you must set the [block\_progress](https://shopify.dev/docs/api/checkout-ui-extensions/configuration#block-progress) capability in your extension's configuration. If you do, then you're expected to inform the buyer why navigation was blocked, either by passing validation errors to the checkout UI or rendering the errors in your extension. `useBuyerJourneyIntercept()` should be called at the top level of the extension, not within an embedded or child component, to avoid errors should the child component get destroyed.

### Parameters

* interceptor

  Interceptor

  required

### Returnsvoid

### Interceptor

A function for intercepting and preventing navigation on checkout. You can block navigation by returning an object with \`{behavior: 'block', reason: InvalidResultReason.InvalidExtensionState, errors?: ValidationErrors\[]}\`. If you do, then you're expected to also update some part of your UI to reflect the reason why navigation was blocked, either by targeting checkout UI fields, passing errors to the page level or rendering the errors in your extension.

* interceptorProps

  ```ts
  InterceptorProps
  ```

InterceptorRequest | Promise\<InterceptorRequest>

```ts
InterceptorRequest | Promise<InterceptorRequest>
```

```ts
(
  interceptorProps: InterceptorProps,
) => InterceptorRequest | Promise<InterceptorRequest>
```

### InterceptorProps

* canBlockProgress

  Whether the interceptor has the capability to block a buyer's progress through checkout. This ability might be granted by a merchant in differing checkout contexts.

  ```ts
  boolean
  ```

```ts
export interface InterceptorProps {
  /**
   * Whether the interceptor has the capability to block a buyer's progress through
   * checkout. This ability might be granted by a merchant in differing checkout contexts.
   */
  canBlockProgress: boolean;
}
```

### InterceptorRequest

```ts
InterceptorRequestAllow | InterceptorRequestBlock
```

### InterceptorRequestAllow

* behavior

  Indicates that the interceptor will allow the buyer's journey to continue.

  ```ts
  'allow'
  ```

* perform

  This callback is called when all interceptors finish. We recommend setting errors or reasons for blocking at this stage, so that all the errors in the UI show up at once.

  ```ts
  (result: InterceptorResult) => void | Promise<void>
  ```

```ts
interface InterceptorRequestAllow {
  /**
   * Indicates that the interceptor will allow the buyer's journey to continue.
   */
  behavior: 'allow';

  /**
   * This callback is called when all interceptors finish. We recommend
   * setting errors or reasons for blocking at this stage, so that all the errors in
   * the UI show up at once.
   * @param result InterceptorResult with behavior as either 'allow' or 'block'
   */
  perform?(result: InterceptorResult): void | Promise<void>;
}
```

### InterceptorResult

```ts
InterceptorResultAllow | InterceptorResultBlock
```

### InterceptorResultAllow

* behavior

  Indicates that the buyer was allowed to progress through checkout.

  ```ts
  'allow'
  ```

```ts
interface InterceptorResultAllow {
  /**
   * Indicates that the buyer was allowed to progress through checkout.
   */
  behavior: 'allow';
}
```

### InterceptorResultBlock

* behavior

  Indicates that some part of the checkout UI intercepted and prevented the buyer’s progress. The buyer typically needs to take some action to resolve this issue and to move on to the next step.

  ```ts
  'block'
  ```

```ts
interface InterceptorResultBlock {
  /**
   * Indicates that some part of the checkout UI intercepted and prevented
   * the buyer’s progress. The buyer typically needs to take some action
   * to resolve this issue and to move on to the next step.
   */
  behavior: 'block';
}
```

### InterceptorRequestBlock

* behavior

  Indicates that the interceptor will block the buyer's journey from continuing.

  ```ts
  'block'
  ```

* errors

  Used to pass errors to the checkout UI, outside your extension's UI boundaries.

  ```ts
  ValidationError[]
  ```

* perform

  This callback is called when all interceptors finish. We recommend setting errors or reasons for blocking at this stage, so that all the errors in the UI show up at once.

  ```ts
  (result: InterceptorResult) => void | Promise<void>
  ```

* reason

  The reason for blocking the interceptor request. This value isn't presented to the buyer, so it doesn't need to be localized. The value is used only for Shopify’s own internal debugging and metrics.

  ```ts
  string
  ```

```ts
interface InterceptorRequestBlock {
  /**
   * Indicates that the interceptor will block the buyer's journey from continuing.
   */
  behavior: 'block';

  /**
   * The reason for blocking the interceptor request. This value isn't presented to
   * the buyer, so it doesn't need to be localized. The value is used only for Shopify’s
   * own internal debugging and metrics.
   */
  reason: string;

  /**
   * Used to pass errors to the checkout UI, outside your extension's UI boundaries.
   */
  errors?: ValidationError[];

  /**
   * This callback is called when all interceptors finish. We recommend
   * setting errors or reasons for blocking at this stage, so that all the errors in
   * the UI show up at once.
   * @param result InterceptorResult with behavior as either 'allow' or 'block'
   */
  perform?(result: InterceptorResult): void | Promise<void>;
}
```

### ValidationError

* message

  Error message to be displayed to the buyer.

  ```ts
  string
  ```

* target

  The checkout UI field that the error is associated with. Example: \`$.cart.deliveryGroups\[0].deliveryAddress.countryCode\` See the \[supported targets]\(/docs/api/functions/reference/cart-checkout-validation/graphql#supported-targets) for more information.

  ```ts
  string
  ```

```ts
export interface ValidationError {
  /**
   * Error message to be displayed to the buyer.
   */
  message: string;
  /**
   * The checkout UI field that the error is associated with.
   *
   * Example: `$.cart.deliveryGroups[0].deliveryAddress.countryCode`
   *
   * See the [supported targets](/docs/api/functions/reference/cart-checkout-validation/graphql#supported-targets)
   * for more information.
   */
  target?: string;
}
```

## use​Buyer​Journey​Steps()

Returns all possible steps a buyer can take to complete the checkout. These steps may vary depending on the type of checkout or the shop's configuration.

### Returns

* BuyerJourneyStep\[]

### BuyerJourneyStep

* disabled

  The disabled state of the buyer journey step. This value will be true if the buyer has not reached the step yet. For example, if the buyer has not reached the \`shipping\` step yet, \`shipping\` would be disabled.

  ```ts
  boolean
  ```

* handle

  The handle that uniquely identifies the buyer journey step.

  ```ts
  BuyerJourneyStepHandle
  ```

* label

  The localized label of the buyer journey step.

  ```ts
  string
  ```

* to

  The url of the buyer journey step. This property leverages the \`shopify:\` protocol E.g. \`shopify:cart\` or \`shopify:checkout/information\`.

  ```ts
  string
  ```

```ts
export interface BuyerJourneyStep {
  /**
   * The handle that uniquely identifies the buyer journey step.
   */
  handle: BuyerJourneyStepHandle;
  /**
   * The localized label of the buyer journey step.
   */
  label: string;
  /**
   * The url of the buyer journey step. This property leverages the `shopify:` protocol
   * E.g. `shopify:cart` or `shopify:checkout/information`.
   */
  to: string;
  /**
   * The disabled state of the buyer journey step. This value will be true if the buyer has not reached the step yet.
   *
   * For example, if the buyer has not reached the `shipping` step yet, `shipping` would be disabled.
   */
  disabled: boolean;
}
```

### BuyerJourneyStepHandle

\| handle | Description | |---|---| | \`cart\` | The cart page. | | \`checkout\` | A one-page checkout, including Shop Pay. | | \`information\` | The contact information step of a three-page checkout. | | \`shipping\` | The shipping step of a three-page checkout. | | \`payment\` | The payment step of a three-page checkout. | | \`review\` | The step after payment where the buyer confirms the purchase. Not all shops are configured to have a review step. | | \`thank-you\` | The page displayed after the purchase, thanking the buyer. | | \`unknown\` | An unknown step in the buyer journey. |

```ts
'cart' | 'checkout' | 'information' | 'shipping' | 'payment' | 'review' | 'thank-you' | 'unknown'
```

## use​Buyer​Journey​Active​Step()

Returns the buyer journey step that the buyer is currently on.

### Returns

* BuyerJourneyStep | undefined

### BuyerJourneyStep

* disabled

  The disabled state of the buyer journey step. This value will be true if the buyer has not reached the step yet. For example, if the buyer has not reached the \`shipping\` step yet, \`shipping\` would be disabled.

  ```ts
  boolean
  ```

* handle

  The handle that uniquely identifies the buyer journey step.

  ```ts
  BuyerJourneyStepHandle
  ```

* label

  The localized label of the buyer journey step.

  ```ts
  string
  ```

* to

  The url of the buyer journey step. This property leverages the \`shopify:\` protocol E.g. \`shopify:cart\` or \`shopify:checkout/information\`.

  ```ts
  string
  ```

```ts
export interface BuyerJourneyStep {
  /**
   * The handle that uniquely identifies the buyer journey step.
   */
  handle: BuyerJourneyStepHandle;
  /**
   * The localized label of the buyer journey step.
   */
  label: string;
  /**
   * The url of the buyer journey step. This property leverages the `shopify:` protocol
   * E.g. `shopify:cart` or `shopify:checkout/information`.
   */
  to: string;
  /**
   * The disabled state of the buyer journey step. This value will be true if the buyer has not reached the step yet.
   *
   * For example, if the buyer has not reached the `shipping` step yet, `shipping` would be disabled.
   */
  disabled: boolean;
}
```

### BuyerJourneyStepHandle

\| handle | Description | |---|---| | \`cart\` | The cart page. | | \`checkout\` | A one-page checkout, including Shop Pay. | | \`information\` | The contact information step of a three-page checkout. | | \`shipping\` | The shipping step of a three-page checkout. | | \`payment\` | The payment step of a three-page checkout. | | \`review\` | The step after payment where the buyer confirms the purchase. Not all shops are configured to have a review step. | | \`thank-you\` | The page displayed after the purchase, thanking the buyer. | | \`unknown\` | An unknown step in the buyer journey. |

```ts
'cart' | 'checkout' | 'information' | 'shipping' | 'payment' | 'review' | 'thank-you' | 'unknown'
```

### Examples

* #### Block progress and show error for a checkout UI field

  ##### Description

  Intercept and prevent a buyer's progress through checkout while targeting a specific checkout UI field. See the \[validation tutorial]\(/docs/apps/checkout/validation) for more examples and best practices.

  ##### Preact

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

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

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

  function Extension() {
    useBuyerJourneyIntercept(
      ({canBlockProgress}) => {
        return canBlockProgress &&
          shopify.shippingAddress.value
            ?.countryCode &&
          shopify.shippingAddress.value
            .countryCode !== 'CA'
          ? {
              behavior: 'block',
              reason: 'Invalid shipping country',
              errors: [
                {
                  message:
                    'Sorry, we can only ship to Canada',
                  // Show an error underneath the country code field
                  target:
                    '$.cart.deliveryGroups[0].deliveryAddress.countryCode',
                },
                {
                  // In addition, show an error at the page level
                  message:
                    'Please use a different address.',
                },
              ],
            }
          : {
              behavior: 'allow',
            };
      },
    );

    return null;
  }
  ```

## Examples

In addition to targeting checkout UI fields, you can also pass errors to the page level or render the error in your extension.

Block progress and show error at page level

Intercept and prevent a buyer's progress through checkout while displaying an error message at the page level. See the [validation tutorial](https://shopify.dev/docs/apps/checkout/validation) for more examples and best practices.

Block progress and show error in your extension

Intercept and prevent a buyer's progress through checkout while displaying an error message in your extension. See the [validation tutorial](https://shopify.dev/docs/apps/checkout/validation) for more examples and best practices.

### Examples

* #### Block progress and show error at page level

  ##### Description

  Intercept and prevent a buyer's progress through checkout while displaying an error message at the page level. See the \[validation tutorial]\(/docs/apps/checkout/validation) for more examples and best practices.

  ##### Preact

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

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

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

  function Extension() {
    useBuyerJourneyIntercept(
      ({canBlockProgress}) => {
        return canBlockProgress &&
          shopify.shippingAddress.value
            ?.countryCode &&
          shopify.shippingAddress.value
            .countryCode !== 'CA'
          ? {
              behavior: 'block',
              reason: 'Invalid shipping country',
              errors: [
                {
                  // An error without a `target` property is shown at page level
                  message:
                    'Sorry, we can only ship to Canada',
                },
              ],
            }
          : {
              behavior: 'allow',
            };
      },
    );

    return null;
  }
  ```

* #### Block progress and show error in your extension

  ##### Description

  Intercept and prevent a buyer's progress through checkout while displaying an error message in your extension. See the \[validation tutorial]\(/docs/apps/checkout/validation) for more examples and best practices.

  ##### Preact

  ```jsx
  import '@shopify/ui-extensions/preact';
  import {render} from 'preact';
  import {useState} from 'preact/hooks';

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

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

  function Extension() {
    const [showError, setShowError] =
      useState(false);

    useBuyerJourneyIntercept(
      ({canBlockProgress}) => {
        return canBlockProgress &&
          shopify.target.value.quantity > 1
          ? {
              behavior: 'block',
              reason: 'limited stock',
              perform: (result) => {
                if (result.behavior === 'block') {
                  setShowError(true);
                }
              },
            }
          : {
              behavior: 'allow',
              perform: () => {
                setShowError(false);
              },
            };
      },
    );

    return showError ? (
      <s-banner tone="critical">
        This item has a limit of one per customer.
      </s-banner>
    ) : null;
  }
  ```

## Related

[![](https://shopify.dev/images/icons/32/tutorial.png)![](https://shopify.dev/images/icons/32/tutorial-dark.png)](https://shopify.dev/docs/apps/checkout/validation/fields)

[TutorialValidating fields at checkout](https://shopify.dev/docs/apps/checkout/validation/fields)

[![](https://shopify.dev/images/icons/32/blocks.png)![](https://shopify.dev/images/icons/32/blocks-dark.png)](https://shopify.dev/docs/api/checkout-ui-extensions/targets)

[ReferenceTargets](https://shopify.dev/docs/api/checkout-ui-extensions/targets)

[![](https://shopify.dev/images/icons/32/apps.png)![](https://shopify.dev/images/icons/32/apps-dark.png)](https://shopify.dev/docs/api/checkout-ui-extensions/components)

[ReferenceComponents](https://shopify.dev/docs/api/checkout-ui-extensions/components)

[![](https://shopify.dev/images/icons/32/gear.png)![](https://shopify.dev/images/icons/32/gear-dark.png)](https://shopify.dev/docs/api/checkout-ui-extensions/configuration)

[ReferenceConfiguration](https://shopify.dev/docs/api/checkout-ui-extensions/configuration)

[![](https://shopify.dev/images/icons/32/tutorial.png)![](https://shopify.dev/images/icons/32/tutorial-dark.png)](https://shopify.dev/apps/checkout)

[LearnTutorials](https://shopify.dev/apps/checkout)