A custom LexicalJs markdown transformer for code blocks

lexical_code_markdown_transformer.ts

const CODE: TextMatchTransformer = {
  dependencies: [CodeNode],
  export: (node: LexicalNode) => {
    if (!$isCodeNode(node)) {
      return null;
    }
    const textContent = node.getTextContent();
    return '```' + (node.getLanguage() ?? '') + (textContent ? '\n' + textContent : '') + '\n' + '```';
  },
  importRegExp: /```$/,
  regExp: /```$/,
  trigger: '`',
  replace: (textNode) => {
    const codeNode = $createCodeNode();
    const textNodeClone = $createTextNode(textNode.getTextContent().replace(/```$/, ''));
    const textNodeParent = textNode.getParent();
    const selection = $getSelection();
    if (textNodeParent) {
      const siblings = textNodeParent.getChildren();
      if (siblings.length > 2 || (siblings.length > 1 && textNode === siblings.at(-1))) {
        selection?.insertNodes([codeNode]);
      } else {
        if ($isRangeSelection(selection)) {
          codeNode.append(textNode);
          $setBlocksType(selection, () => codeNode);
        }
      }
      textNode.replace(textNodeClone);
    }
    codeNode.select(0, 0);
  },
  type: 'text-match',
};