import { useEffect } from 'react'; /* * React component that manages `is-section-*` and `is-group-*` class names on the * element. When the `section` and `group` props get updated, it adds, removes and replaces * CSS classes accordingly. * * TODO: reconsider if these classnames are really needed on and whether having them * on `div.layout` could be sufficient to satisfy all theming and styling requirements. * `div.layout` has the advantage of being maintained by React, where class names can be * specified declaratively and the DOM diffing and patching is done by React itself. */ function useBodyClass( prefix, value ) { useEffect( () => { // if value is empty-ish, don't add or remove any CSS classes if ( ! value ) { return; } // Remove any existing classes with the same prefix, coming from example from a // server HTML markup. There should be max one class name with a gived `prefix` // at any one time. We're removing existing classes only when `value` is not `null`, // i.e., when we actually have a class name to add and want to prevent duplicate one. for ( const className of document.body.classList ) { if ( className.startsWith( prefix ) ) { document.body.classList.remove( className ); } } // convert the value (section or group name) to a CSS class name const className = prefix + value; // add the CSS class to body when performing the effect document.body.classList.add( className ); // remove the CSS class from body in the effect cleanup function return () => document.body.classList.remove( className ); }, [ prefix, value ] ); } /** * @param {{group?: string, section?: string, bodyClass?: string[]}} props */ export default function BodySectionCssClass( { group, section, layoutFocus, bodyClass } ) { useBodyClass( 'is-group-', group ); useBodyClass( 'is-section-', section ); useBodyClass( 'is-focus-', layoutFocus ); useEffect( () => { if ( ! Array.isArray( bodyClass ) || bodyClass.length === 0 ) { return; } bodyClass.forEach( ( className ) => { document.body.classList.add( className ); } ); return () => { bodyClass.forEach( ( className ) => { document.body.classList.remove( className ); } ); }; }, [ bodyClass ] ); return null; }