| import { useEffect } from 'react'; | |
| /* | |
| * React component that manages `is-section-*` and `is-group-*` class names on the <body> | |
| * 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 <body> 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; | |
| } | |