Need to add JS script in checkout page using app

Retired Boards Appdev Extensions

Topic summary

Goal: add a custom JavaScript snippet to the checkout via an app.

Key update: Direct JS injection into checkout is not allowed for stores using Checkout Extensibility. Instead, a Checkout UI extension must be created and added through the Checkout Editor.

Context: Checkout UI extensions are app-based components that integrate with defined extension points in the checkout, providing sanctioned ways to customize behavior and UI without arbitrary scripts.

Open questions from the author:

  • Can a Checkout UI extension be developed when the app stack is Laravel (i.e., whether Laravel can be used for building/hosting the extension)?
  • If not feasible, is there an API-based method to programmatically set the “shipping method notice” text field, possibly during app installation?

Status: No responses yet to the Laravel compatibility or the API approach; discussion remains open.

Summarized with AI on December 20. AI used: gpt-5.
1

I’ve developed an app and now I want to use it to inject a custom JavaScript script into the checkout page.

Please advice, thanks in advance.

2

Hi Ashishgaur,

It’s not possible to inject JS scripts onto checkout pages that are migrated to checkout extensibility. You’ll have to create a Checkout UI extension that can be added to a checkout page via the checkout editor.

3

Thanks Liam,

I’m a Laravel developer and have built an app using Laravel. Can I use Laravel to create a Checkout UI extension for Shopify?

If that’s not possible, is there a way to programmatically set the “shipping method notice” text field via API or during the app installation process?