Project Overview

Shopify announced the deprecation of Script Editor — a tool many Shopify Plus merchants had been using for years to customise checkout pricing and discount behaviour. I led the end-to-end migration of a multi-store merchant's entire Script Editor logic to the modern, supported Shopify Functions platform, ensuring no disruption to their checkout experience and future-proofing their customisations against platform changes.

Migration Process

Audit & Analysis

• Conducted a full audit of all existing Script Editor scripts across the merchant's Shopify Plus stores — documenting discount rules, cart validation conditions, and checkout transformation logic.
• Identified which scripts could be directly ported vs. those requiring re-architecture due to Shopify Functions' new execution model.

Shopify Functions Built

• Discount Functions: Rebuilt all discount logic as Shopify Discount Functions (Wasm/JS) — applying percentage, fixed-amount, and tiered discounts based on configurable business rules that merchants could update from the app admin without developer involvement.
• Cart Validation Functions: Built Cart Validation Functions to enforce purchase constraints — minimum/maximum quantities, product combination rules, and customer-segment-specific restrictions — with clear, localised error messages.
• Cart Transformation Function: Implemented a Cart Transform Function to modify cart line items at checkout, enabling bundle splitting, free gift logic, and custom price overrides.

Theme App Extension for Storefront Logic

• Built a Theme App Extension that injects JavaScript into the storefront for add/remove controls and quantity limiting logic — with all conditions dynamically configurable from the app admin panel.
• Ensured storefront behaviour stayed consistent with checkout-level functions, delivering a seamless end-to-end customer experience.

Merchant Settings UI — Remix + Polaris

• Developed a full merchant-facing settings page within a Remix-based Shopify app using Polaris web components — allowing non-technical staff to configure all discount rules, validation conditions, and transformation logic without code changes.
• Settings were persisted in Prisma-backed database and injected into Function metafield configurations at save time.

Results

• Successfully migrated 100% of Script Editor logic to Shopify Functions ahead of the deprecation deadline.
• Merchants retained full checkout customisation capability with no disruption to live stores during transition.
• Merchant teams gained self-service control over business rules — reducing developer dependency for routine checkout logic changes.