How The4 built custom delivery-schedule logic for Towards.jp

About:

Towards.jp is a Japanese online retailer selling interior and lighting products — from handles, knobs and lighting parts to bulbs and art pieces. Their catalogue mixes product types with very different stock and delivery behaviour.

Industry:

Interiors, lighting & hardware

Some of the most valuable Shopify work is invisible: business logic that quietly does the right thing on every page. Towards.jp needed their delivery-schedule messaging to behave differently depending on product type, stock status and cart contents — a deceptively complex set of rules. Here's how The4 built it.

The Challenges

Towards.jp wanted the delivery-schedule information shown to customers to follow a precise, conditional set of rules — without disturbing the parts of the store that already worked:

• Apply new delivery-schedule behaviour to three product types (handles/knobs, lighting parts and bulbs) based on whether each item was in or out of stock.
• Keep the existing logic untouched for the Lighting collection and Art product type.
• Handle the cart as a priority case: when the cart contains a Lighting or Art product, the whole cart's delivery schedule should follow Lighting/Art rules — otherwise, the new per-type logic applies.

The Solutions

The4 implemented the full rule set as custom logic across both the product page and the cart, working from a precise specification.

Stock-aware logic on the product page

For the three new product types, we built the delivery schedule to respond to stock status — hiding or showing the schedule based on whether the item was in or out of stock — while leaving the existing Lighting and Art behaviour exactly as it was.

Priority logic in the cart

The cart was the hard part. We implemented a priority rule: if the cart contains any Lighting or Art product, the entire cart's delivery schedule follows the Lighting/Art logic (in- or out-of-stock); only when no Lighting or Art item is present does the new per-type logic take over. The result is consistent, correct messaging no matter what combination a customer adds to their cart.

The Results

The4 delivered a complete, custom delivery-schedule system — stock-aware on product pages and priority-driven in the cart — built to an exact specification and signed off on completion, with the store's existing logic left intact.

Conclusion

Off-the-shelf themes cover the common cases; real businesses often need logic that fits their exact rules. The Towards.jp project shows The4 handling genuinely complex, conditional business logic across product and cart pages — cleanly, and without breaking what already worked. If your store needs custom logic done right, this is the kind of work our team does every day.

Need custom Shopify logic? Explore The4's Shopify services, or browse our premium Shopify themes trusted by 48,000+ merchants worldwide.