Build a pre-purchase product offer checkout UI extension

A pre-purchase product offer is an additional sales opportunity that's displayed to customers before they complete checkout. Pre-purchase product offers can help to increase a store's average order value.

In this tutorial, you'll use checkout UI extensions to build a pre-purchase upsell offer that prompts the customer to add a product to their order.

Before you start, review the product offer checkout UI extension UX guidelines.

Shopify Plus

Checkout UI extensions are available only to Shopify Plus merchants.

Anchor to What you'll learnWhat you'll learn

In this tutorial, you'll learn how to do the following:

Generate a checkout UI extension that appears in the checkout flow using Shopify CLI.
Set up configurations for your checkout UI extension in the extension TOML file.
Query the Storefront API from the extension code to get product data.
Use the Checkout UI component library to add new user interface to the checkout.
Use the checkout UI extension API to read and write cart information.

Requirements

You've created a Partner account.

You've created a new development store with the following:
- Generated test data
- Checkout and Customer Accounts Extensibility developer preview enabled
You've created an app that uses Shopify CLI 3.0 or higher.

Project

Extension:

View on GitHub

Anchor to Create a checkout UI extensionCreate a checkout UI extension

To create a checkout UI extension, you'll use Shopify CLI, which generates starter code for building your extension.

To create a checkout UI extension, you can use Shopify CLI, which generates starter code for building your extension and automates common development tasks.

Navigate to your app directory:

Terminal
cd <directory>
Run the following command to create a new checkout UI extension:

Terminal
shopify app generate extension --template checkout_ui --name my-checkout-ui-extension
Select a language for your extension. You can choose from TypeScript, JavaScript, TypeScript React, or JavaScript React.

Tip
TypeScript or JavaScript is suitable for smaller projects that require a more straightforward API. TypeScript React or JavaScript React is suitable when you want an easy model for mapping state updates to UI updates. With JavaScript or TypeScript, you need to map state updates yourself. This process is similar to writing an application targeting the DOM, versus using react-dom.

You should now have a new extension directory in your app's directory. The extension directory includes the extension script at src/index.{file-extension}. The following is an example directory structure:

Checkout UI extension file structure
└── my-app
└── extensions
└── my-checkout-ui-extension
├── src
│ └── Checkout.jsx OR Checkout.js // The index page of the checkout UI extension
├── locales
│ ├── en.default.json // The default locale for the checkout UI extension
│ └── fr.json // The locale file for non-regional French translations
├── shopify.extension.toml // The config file for the checkout UI extension
└── package.json

Start your development server to build and preview your app:

Terminal
shopify app dev

To learn about the processes that are executed when you run dev, refer to the Shopify CLI command reference.
Press p to open the developer console. In the developer console page, click on the preview link for your extension.

Anchor to Set up an extension targetSet up an extension target

Set up a target for your checkout UI extension. Targets control where your extension renders in the checkout flow.

Anchor to Export the target from your script fileExport the target from your script file

In your Checkout.jsx file, set the entrypoints for the checkout extension, and then export them so they can be referenced in your configuration.

For each target that you want to use, create a reactExtension function that references your target, and export it using the default export.

This example code uses the default purchase.checkout.block.render extension target. This target lets merchants choose where they want the extension to appear using the checkout editor, and will render regardless of which checkout features are available.

You can update the checkout URL to test the extension in different locations in the checkout.

If you want the extension to render in only certain places, then use a static target.

reactExtension purchase.checkout.block.render

/extensions/product-offer/src/Checkout.jsx

import React, { useEffect, useState } from "react";

import {

reactExtension,

Divider,

Image,

Banner,

Heading,

Button,

InlineLayout,

BlockStack,

Text,

SkeletonText,

SkeletonImage,

useCartLines,

useApplyCartLinesChange,

useApi,

} from "@shopify/ui-extensions-react/checkout";

// Set up the entry point for the extension

export default reactExtension("purchase.checkout.block.render", () => <App />);

function App() {

const { query, i18n } = useApi();

const applyCartLinesChange = useApplyCartLinesChange();

const [products, setProducts] = useState([]);

const [loading, setLoading] = useState(false);

const [adding, setAdding] = useState(false);

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

const lines = useCartLines();

useEffect(() => {

fetchProducts();

}, []);

useEffect(() => {

if (showError) {

const timer = setTimeout(() => setShowError(false), 3000);

Anchor to Reference the extension targets in your configuration fileReference the extension targets in your configuration file

You can define more than one target so that app users can add the extension to multiple locations in the checkout.

In your checkout UI extension's configuration file, for each of your targets, create an [[extensions.targeting]] section with the following information:

module: The path to the file that contains the extension code.
target: An identifier that specifies where you're injecting code into Shopify. This needs to match the target that you exported from your file/s.

shopify.extension.toml is the configuration file for your extension. It contains basic information and settings.

Note

Whenever you edit your extension configuration file, you need to restart your server for the changes to take effect.

Terminal

shopify app dev

/extensions/product-offer/shopify.extension.toml

# Learn more about configuring your checkout UI extension:

# https://shopify.dev/api/checkout-extensions/checkout/configuration

# The version of APIs your extension will receive. Learn more:

# https://shopify.dev/docs/api/usage/versioning

api_version = "2024-04"

[[extensions]]

name = "product-offer"

type = "ui_extension"

handle = "product-offer"

# Controls where in Shopify your extension will be injected,

# and the file that contains your extension’s source code. Learn more:

# https://shopify.dev/docs/api/checkout-ui-extensions/unstable/extension-targets-overview

[[extensions.targeting]]

module = "./src/Checkout.jsx"

target = "purchase.checkout.block.render"

[extensions.capabilities]

api_access = true

Anchor to Retrieve product dataRetrieve product data

Now that you've set up the extension target, you'll set up products so that you can display them to customers for the product offer.

Anchor to Request API accessRequest API access

Configure your extension to make calls to the Storefront API. In your checkout UI extension's configuration file, create an [extensions.capabilities] section with api_access set to true.

Learn more about requesting Storefront API access for your extension.

To retrieve data from an external source using a checkout UI extension, you need to request the network access capability instead of the API access capability.

/extensions/product-offer/shopify.extension.toml

# Learn more about configuring your checkout UI extension:

# https://shopify.dev/api/checkout-extensions/checkout/configuration

# The version of APIs your extension will receive. Learn more:

# https://shopify.dev/docs/api/usage/versioning

api_version = "2024-04"

[[extensions]]

name = "product-offer"

type = "ui_extension"

handle = "product-offer"

# Controls where in Shopify your extension will be injected,

# and the file that contains your extension’s source code. Learn more:

# https://shopify.dev/docs/api/checkout-ui-extensions/unstable/extension-targets-overview

[[extensions.targeting]]

module = "./src/Checkout.jsx"

target = "purchase.checkout.block.render"

[extensions.capabilities]

api_access = true

Anchor to Retrieve productsRetrieve products

Set up a function that handles retrieving your products, using the query helper function of the StandardApi Checkout API object.

Query the Storefront API Products resource. This query fetches the first five products in the store. Store the products in an array so you can reference the data later.

The StandardApi Checkout API object is automatically made available to all targets.

In a production-ready app, you might query your own database to retrieve a list of products to offer.

For more examples of querying the Storefront API, refer to the Storefront API learning kit.

query StandardApi Products

/extensions/product-offer/src/Checkout.jsx

import React, { useEffect, useState } from "react";

import {

reactExtension,

Divider,

Image,

Banner,

Heading,

Button,

InlineLayout,

BlockStack,

Text,

SkeletonText,

SkeletonImage,

useCartLines,

useApplyCartLinesChange,

useApi,

} from "@shopify/ui-extensions-react/checkout";

// Set up the entry point for the extension

export default reactExtension("purchase.checkout.block.render", () => <App />);

function App() {

const { query, i18n } = useApi();

const applyCartLinesChange = useApplyCartLinesChange();

const [products, setProducts] = useState([]);

const [loading, setLoading] = useState(false);

const [adding, setAdding] = useState(false);

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

const lines = useCartLines();

useEffect(() => {

fetchProducts();

}, []);

useEffect(() => {

if (showError) {

const timer = setTimeout(() => setShowError(false), 3000);

Anchor to Retrieve cart dataRetrieve cart data

Use the useCartLines hook to retrieve the current line items of the cart.

useCartLines is a React hook that lets you subscribe to cart data. To learn more about the hooks available for checkout UI extensions, refer to the Checkout UI extension reference.

useCartLines

/extensions/product-offer/src/Checkout.jsx

import React, { useEffect, useState } from "react";

import {

reactExtension,

Divider,

Image,

Banner,

Heading,

Button,

InlineLayout,

BlockStack,

Text,

SkeletonText,

SkeletonImage,

useCartLines,

useApplyCartLinesChange,

useApi,

} from "@shopify/ui-extensions-react/checkout";

// Set up the entry point for the extension

export default reactExtension("purchase.checkout.block.render", () => <App />);

function App() {

const { query, i18n } = useApi();

const applyCartLinesChange = useApplyCartLinesChange();

const [products, setProducts] = useState([]);

const [loading, setLoading] = useState(false);

const [adding, setAdding] = useState(false);

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

const lines = useCartLines();

useEffect(() => {

fetchProducts();

}, []);

useEffect(() => {

if (showError) {

const timer = setTimeout(() => setShowError(false), 3000);

Anchor to Filter productsFilter products

Create a function to compare the cart contents to the products that you retrieved from the Storefront API to ensure that you don't offer a product that's already in the cart.

/extensions/product-offer/src/Checkout.jsx

import React, { useEffect, useState } from "react";

import {

reactExtension,

Divider,

Image,

Banner,

Heading,

Button,

InlineLayout,

BlockStack,

Text,

SkeletonText,

SkeletonImage,

useCartLines,

useApplyCartLinesChange,

useApi,

} from "@shopify/ui-extensions-react/checkout";

// Set up the entry point for the extension

export default reactExtension("purchase.checkout.block.render", () => <App />);

function App() {

const { query, i18n } = useApi();

const applyCartLinesChange = useApplyCartLinesChange();

const [products, setProducts] = useState([]);

const [loading, setLoading] = useState(false);

const [adding, setAdding] = useState(false);

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

const lines = useCartLines();

useEffect(() => {

fetchProducts();

}, []);

useEffect(() => {

if (showError) {

const timer = setTimeout(() => setShowError(false), 3000);

Anchor to Build the pre-purchase offer UIBuild the pre-purchase offer UI

Build a basic user interface, loading state, and error handling using components from the checkout UI extensions component library.

Anchor to Add add-to-cart functionalityAdd add-to-cart functionality

Use the useApplyCartLinesChange hook to mutate the lines property of the checkout.

useApplyCartLinesChange is a React hook that lets you write cart information. To learn more about the hooks available for checkout UI extensions, refer to the Checkout UI extension reference.

useApplyCartLinesChange

/extensions/product-offer/src/Checkout.jsx

import React, { useEffect, useState } from "react";

import {

reactExtension,

Divider,

Image,

Banner,

Heading,

Button,

InlineLayout,

BlockStack,

Text,

SkeletonText,

SkeletonImage,

useCartLines,

useApplyCartLinesChange,

useApi,

} from "@shopify/ui-extensions-react/checkout";

// Set up the entry point for the extension

export default reactExtension("purchase.checkout.block.render", () => <App />);

function App() {

const { query, i18n } = useApi();

const applyCartLinesChange = useApplyCartLinesChange();

const [products, setProducts] = useState([]);

const [loading, setLoading] = useState(false);

const [adding, setAdding] = useState(false);

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

const lines = useCartLines();

useEffect(() => {

fetchProducts();

}, []);

useEffect(() => {

if (showError) {

const timer = setTimeout(() => setShowError(false), 3000);

Anchor to Build the offer UIBuild the offer UI

Using Checkout UI components, build a basic UI for the product offer.

Checkout UI extensions are limited to specific UI components exposed by the platform for security reasons. Checkout UI components allow you to create a UI that feels seamless within the checkout experience, and that inherits a merchant's brand settings.

BlockStack Divider Heading InlineLayout Image Text

/extensions/product-offer/src/Checkout.jsx

import React, { useEffect, useState } from "react";

import {

reactExtension,

Divider,

Image,

Banner,

Heading,

Button,

InlineLayout,

BlockStack,

Text,

SkeletonText,

SkeletonImage,

useCartLines,

useApplyCartLinesChange,

useApi,

} from "@shopify/ui-extensions-react/checkout";

// Set up the entry point for the extension

export default reactExtension("purchase.checkout.block.render", () => <App />);

function App() {

const { query, i18n } = useApi();

const applyCartLinesChange = useApplyCartLinesChange();

const [products, setProducts] = useState([]);

const [loading, setLoading] = useState(false);

const [adding, setAdding] = useState(false);

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

const lines = useCartLines();

useEffect(() => {

fetchProducts();

}, []);

useEffect(() => {

if (showError) {

const timer = setTimeout(() => setShowError(false), 3000);

Anchor to Build a loading stateBuild a loading state

Use checkout components, including SkeletonText and SkeletonImage, to build a loading state to display while the product variants are being fetched.

A loading state lets the customer know that content is being rendered, improving the perceived performance of the checkout.

BlockStack Button Divider Heading InlineLayout SkeletonImage SkeletonText

/extensions/product-offer/src/Checkout.jsx

import React, { useEffect, useState } from "react";

import {

reactExtension,

Divider,

Image,

Banner,

Heading,

Button,

InlineLayout,

BlockStack,

Text,

SkeletonText,

SkeletonImage,

useCartLines,

useApplyCartLinesChange,

useApi,

} from "@shopify/ui-extensions-react/checkout";

// Set up the entry point for the extension

export default reactExtension("purchase.checkout.block.render", () => <App />);

function App() {

const { query, i18n } = useApi();

const applyCartLinesChange = useApplyCartLinesChange();

const [products, setProducts] = useState([]);

const [loading, setLoading] = useState(false);

const [adding, setAdding] = useState(false);

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

const lines = useCartLines();

useEffect(() => {

fetchProducts();

}, []);

useEffect(() => {

if (showError) {

const timer = setTimeout(() => setShowError(false), 3000);

Anchor to Build an error handling UIBuild an error handling UI

If there's an error adding a product on offer, then use the Banner component to communicate any errors to the user.

For example, you might need to display an error to the customer if the offered product is out of stock.

Banner

/extensions/product-offer/src/Checkout.jsx

import React, { useEffect, useState } from "react";

import {

reactExtension,

Divider,

Image,

Banner,

Heading,

Button,

InlineLayout,

BlockStack,

Text,

SkeletonText,

SkeletonImage,

useCartLines,

useApplyCartLinesChange,

useApi,

} from "@shopify/ui-extensions-react/checkout";

// Set up the entry point for the extension

export default reactExtension("purchase.checkout.block.render", () => <App />);

function App() {

const { query, i18n } = useApi();

const applyCartLinesChange = useApplyCartLinesChange();

const [products, setProducts] = useState([]);

const [loading, setLoading] = useState(false);

const [adding, setAdding] = useState(false);

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

const lines = useCartLines();

useEffect(() => {

fetchProducts();

}, []);

useEffect(() => {

if (showError) {

const timer = setTimeout(() => setShowError(false), 3000);

Anchor to Preview the extensionPreview the extension

Preview your extension to make sure that it works as expected.

Anchor to Start your serverStart your server

Run the Shopify CLI dev command to build your app and preview it on your development store.

Make sure that you select a development store that has enabled the developer preview for Checkout and Customer Accounts Extensibility.

In a terminal, navigate to your app directory.
Either start or restart your server to build and preview your app:

Terminal
shopify app dev
Press p to open the developer console.
In the developer console page, click on the preview link for the custom pre-purchase offer extension.

The checkout opens.

This section describes how to solve some potential errors when you run dev for an app that contains a checkout UI extension.

Anchor to Property token errorProperty token error

If you receive the error ShopifyCLI:AdminAPI requires the property token to be set, then you'll need to use the --checkout-cart-url flag to direct Shopify CLI to open a checkout session for you.

Terminal

shopify app dev --checkout-cart-url cart/{product_variant_id}:{quantity}

Anchor to Missing checkout linkMissing checkout link

If you don't receive the test checkout URL when you run dev, then verify the following:

You have a development store populated with products.
You're logged in to the correct Partners organization and development store. To verify, check your app info using the following command:

Terminal
shopify app info

Otherwise, you can manually create a checkout with the following steps:

From your development store's storefront, add some products to your cart.
From the cart, click Checkout.
From directory of the app that contains your extension, run dev to preview your app:

Terminal
shopify app dev
On the checkout page for your store, change the URL by appending the ?dev=https://{tunnel_url}/extensions query string and reload the page. The tunnel_url parameter allows your app to be accessed using a unique HTTPS URL.

You should now see a rendered order note that corresponds to the code in your project template.

Anchor to Test the extensionTest the extension

Preview your new code and ensure that the extension works as designed.

Anchor to Test the extension functionalityTest the extension functionality

With your server running, open the storefront of your development store.
Add a product to the cart and then check out.

Your placeholder extension is replaced with your new extension code that offers a product from the store, under the heading You might also like.
Click Add to add the product to the cart.

The product is added to the cart, and the offer is replaced with a new offer. If the product is out of stock, then an error is returned and the offer is replaced with a new offer.
Continue adding products to the cart using the Add button.

After you add multiple offered products to the cart, the extension is hidden.
Complete the checkout.

In the Orders area of the Shopify admin, a new order appears. The order contains the products that you added to the cart, including the offered products.

The product offer section in the checkout.

Troubleshooting

Anchor to Property token errorProperty token error

If you receive the error ShopifyCLI:AdminAPI requires the property token to be set, then you need to use the `--checkout-carturl flag to direct Shopify CLI to open a checkout session for you.

Terminal

shopify app dev --checkout-cart-url cart/{product_variant_id}:{quantity}

When you're ready to release your changes to users, you can create and release an app version. An app version is a snapshot of your app configuration and all extensions.

Navigate to your app directory.
Run the following command.

Optionally, you can provide a name or message for the version using the --version and --message flags.

Terminal
shopify app deploy

Releasing an app version replaces the current active version that's served to stores that have your app installed. It might take several minutes for app users to be upgraded to the new version.

Tip

If you want to create a version, but avoid releasing it to users, then run the deploy command with a --no-release flag. You can release the unreleased app version using Shopify CLI's release command, or through the Partner Dashboard.

/extensions/product-offer/shopify.extension.toml

# Learn more about configuring your checkout UI extension:

# https://shopify.dev/api/checkout-extensions/checkout/configuration

# The version of APIs your extension will receive. Learn more:

# https://shopify.dev/docs/api/usage/versioning

api_version = "2024-04"

[[extensions]]

name = "product-offer"

type = "ui_extension"

handle = "product-offer"

# Controls where in Shopify your extension will be injected,

# and the file that contains your extension’s source code. Learn more:

# https://shopify.dev/docs/api/checkout-ui-extensions/unstable/extension-targets-overview

[[extensions.targeting]]

module = "./src/Checkout.jsx"

target = "purchase.checkout.block.render"

[extensions.capabilities]

api_access = true

Anchor to Tutorial complete!Tutorial complete!

Nice work - what you just built could be used by Shopify merchants around the world! Keep the momentum going with these related tutorials and resources.

Anchor to Next stepsNext steps

Review product offer UX guidelines

Build a good pre-purchase product offer experience by following our UX guidelines.

Localize your extension

Learn how to localize the text and number formats in your extension.

Explore the checkout UI extension component reference

Learn about all of the components that you can use in your checkout UI extension.

Explore the checkout UI extension targets API reference

Learn about the extension targets offered in the checkout.

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