Migrating from Shopify Scripts to Shopify Functions

Deprecated

Shopify Scripts was sunset on June 30, 2026. Any Scripts that were still published on your store have been deactivated and no longer function.

Functions availability

Stores on any plan can use public apps that are distributed through the Shopify App Store and contain functions. Only stores on a Shopify Plus plan can use custom apps that contain Shopify Function APIs.
Some Shopify Functions capabilities are available only to stores on a Shopify Plus plan. See Shopify Function APIs for details.

This guide shows how to migrate your Shopify Scripts to Shopify Functions and validate the new Functions with tagged test customers before enabling them for everyone. Shopify Scripts allowed you to customize cart behavior, shipping, and payment methods in a store. With Shopify Functions, these customizations are now handled through dedicated Function APIs that offer better performance and flexibility.

Anchor to What you'll learnWhat you'll learn

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

Map your Shopify Scripts functionality to the right Shopify Functions.
Verify new Functions with tagged test customers in production.
Enable your verified Functions for all customers.

Anchor to RequirementsRequirements

You have an existing Shopify Script that you want to migrate.
You have access to a dev store for initial testing.
You're familiar with creating Shopify Functions using Shopify CLI.
You can open the Script Editor app in read-only mode to reference your original Script logic. The Script Editor is available until July 30, 2026.

Anchor to Function APIs mappingFunction APIs mapping

Use the following table to map your existing Shopify Script to the appropriate Function API:

Shopify Script type	Shopify Function API	Use case
Line item scripts	Discounts API	Apply discounts to products, or the entire cart.
Line item scripts	Cart Transform API	Modify cart line items (bundle, merge, or add items).
Line item scripts	Cart and Checkout Validation API	Validate cart contents and block checkout under specific conditions.
Shipping scripts	Delivery Customization API and Discounts API	Hide, rename, or reorder delivery methods, and apply discounts to delivery methods.
Payment scripts	Payment Customization API	Hide, rename, or reorder payment methods.

Anchor to Step 1: Add testing logic to your FunctionStep 1: Add testing logic to your Function

In your Shopify Function, add logic to target specific test users. The most reliable method is using customer tags.

Anchor to Tag test customersTag test customers

In the Shopify admin, go to Customers and add a tag like TESTER to customers who should experience the new Function behavior.
In your Function's input query, include customer tag information:

src/run.graphql
query Input {
cart {
buyerIdentity {
customer {
hasAnyTag(tags: ["TESTER"])
}
}
# ... rest of your query
}
}

Anchor to Implement conditional logicImplement conditional logic

Add conditional logic in your Function to only apply new behavior to tagged customers:

File

// Check if the customer has the TESTER tag

let has_tester_tag = input

.cart()

.buyer_identity()

.and_then(|bi| bi.customer())

.map(|customer| customer.has_any_tag())

.unwrap_or(&false);

if *has_tester_tag {

// Apply new Function logic here

// ... your function implementation

} else {

// Untagged customers receive no operations during validation

return Ok(FunctionRunResult { operations: vec![] });

}

const customer = input.cart.buyerIdentity?.customer;

const hasTesterTag = customer?.hasAnyTag ?? false;

if (hasTesterTag) {

// Apply new Function logic here

// ... your function implementation

} else {

// Untagged customers receive no operations during validation

return { operations: [] };

}

Rust

// Check if the customer has the TESTER tag
let has_tester_tag = input
    .cart()
    .buyer_identity()
    .and_then(|bi| bi.customer())
    .map(|customer| customer.has_any_tag())
    .unwrap_or(&false);

if *has_tester_tag {
    // Apply new Function logic here
    // ... your function implementation
} else {
    // Untagged customers receive no operations during validation
    return Ok(FunctionRunResult { operations: vec![] });
}

JavaScript

const customer = input.cart.buyerIdentity?.customer;
const hasTesterTag = customer?.hasAnyTag ?? false;

if (hasTesterTag) {
    // Apply new Function logic here
    // ... your function implementation
} else {
    // Untagged customers receive no operations during validation
    return { operations: [] };
}

Because Shopify Scripts no longer run, untagged customers receive none of this customization while the tag condition is in place. Keep the tagged validation period short, then remove the condition and enable the Function for all customers, as described in Step 3.

Anchor to Step 2: Deploy and test in productionStep 2: Deploy and test in production

You can test your Function in development and production.

Anchor to Development testingDevelopment testing

Test your Function thoroughly in a dev store:

Terminal
shopify app dev

Anchor to Production deployment and testingProduction deployment and testing

Choose one of the following deployment methods:

Anchor to Option A: App with configuration UIOption A: App with configuration UI

If your Function is part of an app with a user interface, then use the app to enable and configure the Function in production.

Anchor to Option B: GraphiQL deploymentOption B: GraphiQL deployment

Note

This method works best for Functions that don't require ongoing merchant configuration.

If you have a custom Function without UI configuration, then complete the following steps:

Use the Shopify GraphiQL App to enable the Function directly.
Retrieve a list of available Functions using this query:

query.graphql
query getFunctions {
shopifyFunctions(first: 100) {
edges {
node {
id
title
apiType
}
}
pageInfo {
hasNextPage
endCursor
}
}
}
Use the Function's id in the appropriate creation mutation for your Function type (for example, discountAutomaticAppCreate or deliveryCustomizationCreate).

Anchor to Step 3: Complete the migrationStep 3: Complete the migration

After you've verified that the Function works correctly:

Remove testing code: Update your Function to remove the customer tag conditional logic.
Deploy the final version:

Terminal
shopify app deploy

Anchor to Best practicesBest practices

Always test in a dev store before deploying to production.
Keep the testing period short to minimize code complexity.
Monitor your store's performance and error logs after migration.
Document any differences in behavior between Scripts and Functions.
Test edge cases that might behave differently between Scripts and Functions.

Anchor to TroubleshootingTroubleshooting

You might encounter the following issue during migration:

Function not triggering: Verify the Function is properly enabled and configured.
Different behavior: Check the input data structure your Function receives.

Anchor to Next stepsNext steps

Learn more about Shopify Functions.

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