From twilight.json to useTheme().settings

Beginner6 min

Settings you declare in twilight.json become merchant choices, arrive with the store settings, and reach components through useTheme().

A theme is used by many merchants, and each wants it a little different: a sticky header here, a dark footer there. You do not write a version per merchant. You declare the choices in twilight.json, the merchant picks, and your components read the picks.

Step through how a switch in twilight.json becomes a value in your component.

1. You declare the settings

In twilight.json your theme lists the choices a merchant can make: switches, dropdowns, texts. Each has an id, and that id is the name your code reads later.

In engine terms

Each settings[] entry has a semantic type (boolean, items, string, static…) and a widget format (switch, dropdown-list, text…). Booleans and strings keep their default in value, dropdowns in selected or value. static entries are headings and lines for the settings screen and hold no value. The manifest also declares "type": "react".

Both ends of one setting

twilight.json (excerpt)

{
  "type": "react",
  "settings": [
    {
      "id": "show_promo_banner",
      "type": "boolean",
      "format": "switch",
      "label": "Show the promo banner",
      "value": true
    }
  ]
}

app/components/PromoBanner.tsx

import { useTheme } from '@salla.sa/twilight-theme-engine/hooks/useTheme';

export function PromoBanner() {
  const { settings, color } = useTheme();
  // Your own id: read it through a cast, and give it the default yourself.
  const show = (settings as Record<string, unknown>).show_promo_banner ?? true;
  if (!show) return null;

  return (
    <div style={{ background: color.primary, color: color.reverse_primary }}>
      Free delivery over 200 SAR
    </div>
  );
}

Below, useTheme() runs against the demo store: expand settings to see the merchant's saved values next to the platform ones.

The merchant's theme colors, font and settings, as the store answers with them.Try this: switch the language pill (top bar, or the ☰ menu on a phone) to en and watch isRTL change.

Storefront canvas · en · LTR

color.primary #ed1c24

color.text #000000

color.reverse_primary #6e0000

font: Dubai · isRTL: false

settings: {…} 26 keys

font: {…} 5 keys

imageZoom: false

show_tags: true

store_color: "#ed1c24"

homepage_type: "custom"

is_custom_css: true

theme_version: "1.188.0"

footer_is_dark: false

topnav_is_dark: false

important_links: true

store_font_type: "default"

enable_more_menu: true

footer_menu_type: "default"

header_is_sticky: true

header_menu_type: "default"

default_font_name: "خط سلة الافتراضي (جديد)"

translations_hash: "1789908891"

sticky_add_to_cart: true

customization_css_ver: 1778680971

is_more_button_enabled: true

slider_background_size: "cover"

vertical_fixed_products: false

enable_add_product_toast: true

squar_photo_bg_image_size: "cover"

is_show_more_detail_enabled: true

is_breadcrumbs_enabled: true

What a theme writes

import { useTheme } from '@salla.sa/twilight-theme-engine/hooks/useTheme';

export function PrimaryButton({ children }: { children: React.ReactNode }) {
  const { color } = useTheme();
  return (
    <button style={{ background: color.primary, color: color.reverse_primary }}>
      {children}
    </button>
  );
}

Why it matters

It works in development and not on a real store: the dev widget filled in your twilight.json default, and the real store has no value for it. Give every read a default in code.
A merchant saves a change and the open page does not follow: the theme is kept from the first render. It shows on the next full page load.
A loader or head function reads a setting through getTwilightContext().settings.theme.settings: same stored values, but never the dev widget's overrides.
A typo in your own id is not caught by TypeScript (the cast accepts any name). Keep your ids in one constants file.

Check yourself

On a published store, what does the engine do with the value you gave a setting in twilight.json?

It uses that value whenever the merchant has not saved oneNothing at runtime: only the dev server reads twilight.json, so defaults belong in your codeIt copies it into getTwilightContext().settings on the first request

Go deeper: useTheme, Theme types, DevSettingsWidget, the theme type marker and store settings. Home page blocks are declared in the same file: see Home page blocks.