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ثيم رائدaren

useDocumentClassOutput

hookAdvancedbrowserlive demo

Returns the merged html and body attributes every useDocumentClass() call has registered, as React props ready to spread.

import { useDocumentClassOutput } from '@salla.sa/twilight-theme-engine/providers';

In plain words

Components can ask for classes and attributes on <body> and <html> with useDocumentClass(). The provider merges all those requests, and useDocumentClassOutput() gives you the merged result as two objects of React props (className instead of class).

Signature

function useDocumentClassOutput(): {
  bodyAttrs: Record<string, string>;   // { className: 'salla-raed color-mode-light rtl …' }
  htmlAttrs: Record<string, string>;   // { lang: 'ar', dir: 'rtl' }
}

Try it live

The merged html and body attributes every useDocumentClass() call on this page has registered, as React props.Try this: turn the marker on: its class joins the theme classes in bodyAttrs.className, and data-playground-demo appears. Turn it off and both go.
Storefront canvas · en · LTR
Runs in the browser…
Controls
mount a component that calls useDocumentClass
What a theme writes
import { useDocumentClass } from '@salla.sa/twilight-theme-engine/hooks/useDocumentClass';
import { useDocumentClassOutput } from '@salla.sa/twilight-theme-engine/providers';

// A page asks for a body class while it is mounted.
export function ProductPage() {
  useDocumentClass({ body: { class: 'playground-demo' } });
  return <main>…</main>;
}

// Anything below TwilightProvider can read the merged result.
export function BodyClassDebug() {
  const { bodyAttrs } = useDocumentClassOutput();
  return <pre>{bodyAttrs.className}</pre>;
}

Example

app/components/BodyClassDebug.tsx
import { useDocumentClassOutput } from '@salla.sa/twilight-theme-engine/providers';

export function BodyClassDebug() {
  const { bodyAttrs, htmlAttrs } = useDocumentClassOutput();
  return <pre>{JSON.stringify({ bodyAttrs, htmlAttrs }, null, 2)}</pre>;
}

How it behaves

  • Merge rules: every class value is split, joined and de-duplicated; any other attribute takes the value of the last registration; empty strings are skipped.

  • It subscribes to the provider's store (useSyncExternalStore), so it renders again whenever a registration changes. With no DocumentClassProvider above it, both objects are empty.

  • The provider applies the attributes to the real <body> and <html> itself, in an effect; this hook only reads them.

Gotchas

  • Its result is empty in the server render. useDocumentClass() registers in an effect, and effects never run on the server, so spreading the result onto <html> or <body> adds nothing to the HTML; docs/20-document-class.md says this hook "makes SSR work". For attributes the server must send, set lang and dir from getTwilightContext() as the reference theme does, or use route staticData.documentAttrs with useAttrs() from /tanstack.

  • Because the server and the browser disagree, render its output only after hydration.

Related

useDocumentClassContext

Low-level access to the store behind useDocumentClass(): register or remove an html and body descriptor under an id you choose.

DocumentClassProvider

Collects every useDocumentClass() request in its tree and applies the merged classes and attributes to the real body and html elements.

TwilightProvider

The component a theme mounts once around its pages; it shares the store, theme, language and navigation with everything inside it.

Source and docs