ProductComparisonButton

Purpose

ProductComparisonButton is the per-product action reusable that adds/removes items from the comparison list.

It exposes comparison toggle behavior used in catalog and product card contexts.

Where it's rendered

It’s rendered in multiple places:

Components/ProductSingle/Default.liquid

Reusables/ProductGridItem/Default.liquid

Reusables/ProductListItem/Default.liquid

From Components/ProductSingle/Default.liquid:

{% render 'Reusables\\ProductComparisonButton\\Default', id: product.id, title: product.title %}

Inputs (Liquid render parameters)

Named parameters:

id

Product id used as the comparison list key.

title

Human-readable product title used for the button title / aria-label.

Template behavior (Liquid + Alpine)

The button is rendered only when the feature flag is enabled:

GlobalData.Settings.ShowProductComparison

It binds Alpine using a factory:

x-data="productcomparisonbuttonreusabledefault.initComponent('{{ id }}')"

The button uses a toggled state class:

:class="` ${productExists ? 'active' : ''}`"

Disabled behavior:

The template binds :disabled="isDisabled".

The JS sets isDisabled when the list is full and the current product is not already in the list.

On click it calls handleClick(...) and passes translated strings (and an HTML snippet that links to /comparison).

Data contract (JS runtime)

Model shape (storefront example)

Example (from a real product model dump) keeping only the relevant fields used by this reusable:

{
  "id": "Product Id",
  "title": "Sample title"
}

Runtime data

Comparison list

Stored in (and retrieved from) productcomparisondefault.

Maximum supported size is 8 items.

Events

The button listens for the comparisonListUpdated event to refresh its state.

It also listens for the storage event when the comparisonSync key changes.

JavaScript

Global object

Global object: productcomparisonbuttonreusabledefault

Liquid wiring:

x-data="productcomparisonbuttonreusabledefault.initComponent('<productId>')"

initComponent(id)

What it does

Returns an Alpine component instance bound to a specific product id.

Key behaviors / edge cases

The returned object holds local state (productExists, isListFull, isDisabled) derived from the comparison list.

Keep the id stable (should be the product id). If you pass a variant id instead, you may end up comparing variants instead of products.

init()

What it does

Loads the comparison list via productcomparisondefault.getList().

Calls updateState().

Subscribes to:

comparisonListUpdated (custom event)

storage event for cross-tab sync (comparisonSync)

Key behaviors / edge cases

If the list changes in another tab, the storage listener keeps the button state in sync.

Don’t remove the storage listener if you want comparison to work reliably across multiple tabs.

updateState()

updateState

What it does

Computes:

productExists: whether the current id is in the list

isListFull: whether list length is >= 8

isDisabled: list is full AND the product is not in the list

Key behaviors / edge cases

A product that is already in the list stays enabled even when the list is full (so it can be removed).

handleClick(addedProduct, removedProduct, addedProductAndListFull, extraText)

What it does

Toggles the product in the list.

Persists the updated list via productcomparisondefault.setList(this.list).

Dispatches comparisonListUpdated with a payload { id, timestamp }.

Displays toast feedback using $store.toast:

When removing: uses removedProduct.

When adding:

uses addedProductAndListFull if list becomes exactly 8

otherwise uses addedProduct

In most cases it includes extraText, which contains the link to /comparison.

Key behaviors / edge cases

When the list becomes empty after removing, it uses a toast call without extraText.

Advice

extraText is HTML (includes an <a>). Ensure it is escaped/sanitized at the point it is constructed in Liquid.

init

Initializes the comparison button state and registers event listeners for list updates (custom event + storage sync).

Global Alpine stores

This reusable uses:

$store.toast

add(...) is called to show user feedback after add/remove.

Services / API calls

No direct API/service calls are made by this reusable.

Dependencies

Liquid: Reusables/ProductComparisonButton/Default.liquid

JS: Reusables/ProductComparisonButton/Default.js

Translations: Reusables/ProductComparisonButton/Default.json

Global JS object: productcomparisondefault (list storage helpers)

Alpine store: $store.toast

Page route: /comparison (used in the toast extra text)

Notes

Rendering is gated by GlobalData.Settings.ShowProductComparison.

The comparison limit is hard-coded to 8 in updateState().

The button title / aria-label includes title passed from Liquid, so send a human-readable product title.

ProductComparisonButton

Purpose#

Where it's rendered#

Inputs (Liquid render parameters)#

Template behavior (Liquid + Alpine)#

Data contract (JS runtime)#

Model shape (storefront example)#

Runtime data#

JavaScript#

Global object#

initComponent(id)#

init()#

updateState()#

updateState#

handleClick(addedProduct, removedProduct, addedProductAndListFull, extraText)#

init#

Global Alpine stores#

Services / API calls#

Dependencies#

Notes#

Purpose

Where it's rendered

Inputs (Liquid render parameters)

Template behavior (Liquid + Alpine)

Data contract (JS runtime)

Model shape (storefront example)

Runtime data

JavaScript

Global object

initComponent(id)

init()

updateState()

updateState

handleClick(addedProduct, removedProduct, addedProductAndListFull, extraText)

init

Global Alpine stores

Services / API calls

Dependencies

Notes