複数行テキストを、pタグとbrタグで整形して表示したい

function changeToParagraphGroup(str) {
  if(!str){
    return [];
  }

  const paragraph_groups = str.split(/\n/).reduce((result, line) => {
    if (result.is_prev_empty) {
      result.group_num++;
    }

    if (line.length === 0 && !result.is_prev_empty) {
      result.is_prev_empty = true;
      return result
    }

    const temp_key = 'paragraph_' + result.group_num;
    if (Object.keys(result.paragraph_groups).indexOf(temp_key) < 0) {
      result.paragraph_groups[temp_key] = [];
    }
    result.paragraph_groups[temp_key].push(line);
    result.is_prev_empty = line.length === 0;

    return result;
  }, {
    group_num: 0,
    is_prev_empty: false,
    paragraph_groups: {}
  }).paragraph_groups;

  return Object.values(paragraph_groups).map( lines => {
    return {
      is_exists : lines.join('').length > 0,
      count : lines.length,
      lines
    }
  });
}