@wordpress/block-editor/src/components/block-styles/utils.js

Generic block editor.

/**
 * External dependencies
 */
import { find } from 'lodash';
/**
 * WordPress dependencies
 */
import TokenList from '@wordpress/token-list';

/**
 * Returns the active style from the given className.
 *
 * @param {Array} styles Block style variations.
 * @param {string} className  Class name
 *
 * @return {Object?} The active style.
 */
export function getActiveStyle( styles, className ) {
	for ( const style of new TokenList( className ).values() ) {
		if ( style.indexOf( 'is-style-' ) === -1 ) {
			continue;
		}

		const potentialStyleName = style.substring( 9 );
		const activeStyle = find( styles, { name: potentialStyleName } );
		if ( activeStyle ) {
			return activeStyle;
		}
	}

	return find( styles, 'isDefault' );
}

/**
 * Replaces the active style in the block's className.
 *
 * @param {string}  className   Class name.
 * @param {Object?} activeStyle The replaced style.
 * @param {Object}  newStyle    The replacing style.
 *
 * @return {string} The updated className.
 */
export function replaceActiveStyle( className, activeStyle, newStyle ) {
	const list = new TokenList( className );

	if ( activeStyle ) {
		list.remove( 'is-style-' + activeStyle.name );
	}

	list.add( 'is-style-' + newStyle.name );

	return list.value;
}