@atlaskit/editor-plugin-code-block-advanced/src/nodeviews/extensions/firstCodeBlockInDocument.ts

CodeBlockAdvanced plugin for @atlaskit/editor-core

import type { Extension } from '@codemirror/state';
import { EditorView as CodeMirror } from '@codemirror/view';

import { editorExperiment } from '@atlaskit/tmp-editor-statsig/editor-experiment';

/**
 * Keeps 'first-node-in-document' class if it was added to a codeBlock by
 * platform/packages/editor/editor-plugin-block-controls/src/pm-plugins/first-node-dec-plugin.ts
 *
 * @param getPos
 * @returns CodeMirror Extension
 * @example
 */
export const firstCodeBlockInDocument = (getPos: () => number | undefined): Extension => {
	if (editorExperiment('platform_editor_controls', 'variant1')) {
		return CodeMirror.editorAttributes.of({
			class: getPos?.() === 0 ? 'first-node-in-document' : '',
		});
	} else {
		return [];
	}
};